0:00:02 > 0:00:05The sun rises on Japan.
0:00:06 > 0:00:10More than 6,000 islands on the edge of the Pacific.
0:00:15 > 0:00:18Life here is at the mercy
0:00:18 > 0:00:21of Earth's most powerful elemental forces.
0:00:27 > 0:00:30From the wilds of the frozen north...
0:00:31 > 0:00:33BIRDS SQUAWK
0:00:33 > 0:00:37..to the subtropical warmth of the south...
0:00:38 > 0:00:42..animals along this chain of islands have had to adapt
0:00:42 > 0:00:45in unique and sometimes bizarre ways.
0:00:51 > 0:00:54Throughout this land, people have developed
0:00:54 > 0:00:58an extraordinary relationship with the natural world...
0:00:58 > 0:01:00BEAR GROWLS
0:01:06 > 0:01:09..trying to capture its fleeting beauty...
0:01:12 > 0:01:15..and tame its spirit.
0:01:16 > 0:01:19But these islands remain wild, mysterious
0:01:19 > 0:01:21and magical.
0:01:22 > 0:01:24This...
0:01:24 > 0:01:26is Japan.
0:01:31 > 0:01:36Japan's great chain of islands stretches for 2,000 miles.
0:01:37 > 0:01:40Right in the middle is its biggest island...
0:01:42 > 0:01:43..Honshu.
0:01:45 > 0:01:49Here is one of the largest urban areas on Earth.
0:01:51 > 0:01:53But this is a wild place too.
0:01:55 > 0:01:59From the volcanic mountains to the edge of the sea,
0:01:59 > 0:02:03people and nature are drawn together in the most extraordinary ways.
0:02:14 > 0:02:15Tokyo.
0:02:15 > 0:02:18Home to over 35 million people.
0:02:20 > 0:02:22It's so densely packed,
0:02:22 > 0:02:25it's hard to imagine there's any room left for nature.
0:02:27 > 0:02:30BIRDSONG
0:02:30 > 0:02:33But as the sun rises on a spring morning,
0:02:33 > 0:02:35something magical is about to happen.
0:02:43 > 0:02:45In the heart of the city,
0:02:45 > 0:02:48thousands of cherry trees are bursting into blossom.
0:02:53 > 0:02:58For just a few fleeting days, everyone celebrates.
0:02:58 > 0:03:01No other event in Honshu is more welcomed.
0:03:05 > 0:03:09This natural event is so important, it makes front-page news.
0:03:11 > 0:03:13Every spring, across Japan,
0:03:13 > 0:03:17people follow the sakura zensen - the cherry forecast -
0:03:17 > 0:03:21eager to see the blossom at its very best.
0:03:39 > 0:03:42The magic is all too brief.
0:03:43 > 0:03:46The petals start to fall almost as soon as they appear.
0:03:54 > 0:03:56Even in this most urban place,
0:03:56 > 0:04:00people still yearn for a connection with nature.
0:04:09 > 0:04:13But Honshu's cities are crowded for a reason.
0:04:23 > 0:04:25Three-quarters of this island is mountainous,
0:04:25 > 0:04:28where fewer people can live.
0:04:28 > 0:04:33Over 20 of these peaks are more than 3,000 metres high,
0:04:33 > 0:04:37pushed up by violent upheavals in the Earth's crust.
0:04:40 > 0:04:43This is no place for humans.
0:04:44 > 0:04:49The Hida Mountains are instead home to Honshu's wildest creatures.
0:05:05 > 0:05:06A black bear.
0:05:10 > 0:05:12And this one's hungry.
0:05:22 > 0:05:27He'll spend eight hours a day flipping rocks, looking for ants.
0:05:29 > 0:05:33It might not seem much to keep a bear going.
0:05:37 > 0:05:39He's not on his own up here.
0:05:40 > 0:05:44A Japanese macaque is also looking for a meal.
0:05:59 > 0:06:03But for these dextrous monkeys there are alternatives.
0:06:05 > 0:06:09These miniature trees, pruned by the elements, are covered in pine nuts.
0:06:10 > 0:06:13Full of fat and easy to reach.
0:06:26 > 0:06:29But despite these rich pickings,
0:06:29 > 0:06:31Honshu's macaques have learned
0:06:31 > 0:06:34that there are even easier ways to make a living.
0:06:34 > 0:06:38But to reach it, they have to venture off the mountain peaks...
0:06:40 > 0:06:43..and that will bring them into contact with people.
0:06:54 > 0:06:58No matter how wild it seems, there's nowhere in Honshu
0:06:58 > 0:07:02where the paths of people and animals don't cross.
0:07:04 > 0:07:07This crowd of macaques is on a mission,
0:07:07 > 0:07:10all heading down the mountain to the same place.
0:07:28 > 0:07:33In among the rocks, there's a pool heated by volcanic springs.
0:07:33 > 0:07:35The temperature of a warm bath,
0:07:35 > 0:07:37it's just the thing in the chilly mountain air.
0:07:39 > 0:07:43This was once a spa for the exclusive use of humans.
0:07:46 > 0:07:50Back in the '60s, one young macaque discovered the hot tub,
0:07:50 > 0:07:52and liked the warmth.
0:07:52 > 0:07:56News spread, and now they've claimed it as their own.
0:07:57 > 0:08:01It's so popular, there can be hundreds of macaques here every day.
0:08:07 > 0:08:09And thousands of adoring tourists
0:08:09 > 0:08:12venture into the mountains to see them.
0:08:13 > 0:08:16These are some of the most photographed animals on Earth.
0:08:23 > 0:08:25But they are not just here for a bath.
0:08:25 > 0:08:27They're onto a very good thing.
0:08:34 > 0:08:38Each macaque has its favourite way of retrieving the treats.
0:08:44 > 0:08:46You can try holding your breath
0:08:46 > 0:08:49and stuffing as much into your mouth as you can.
0:09:10 > 0:09:12But if you don't like getting your hair wet,
0:09:12 > 0:09:14there's a daintier technique.
0:09:14 > 0:09:16One for the more refined.
0:09:42 > 0:09:46At the end of the day, when the tourists have gone home,
0:09:46 > 0:09:48they make their way back to the mountain forest.
0:09:55 > 0:10:00But this is still a wild place, full of dangers for a young macaque.
0:10:05 > 0:10:08It's no place for a swimming lesson.
0:10:08 > 0:10:10MACAQUE SQUEALS
0:10:17 > 0:10:19There are no gentle streams here.
0:10:31 > 0:10:35Water tumbles off these mountains at four tonnes a second.
0:10:47 > 0:10:51The Shomyo Falls are Japan's highest.
0:10:51 > 0:10:54The water cascades over 300 metres -
0:10:54 > 0:10:57taller than the Eiffel Tower.
0:10:58 > 0:11:01Despite falling so far, the water doesn't roar,
0:11:01 > 0:11:03it murmurs.
0:11:05 > 0:11:07People say it sounds like the chanting of prayers.
0:11:16 > 0:11:19It may be a wild journey down the mountains
0:11:19 > 0:11:22but this raging water is about to be tamed.
0:11:33 > 0:11:35As it reaches the foothills,
0:11:35 > 0:11:38the torrents are gradually controlled and channelled.
0:11:42 > 0:11:44With so much pure water on tap,
0:11:44 > 0:11:48people can grow Japan's most important crop.
0:11:51 > 0:11:55These are Honshu's traditional rice paddies.
0:12:07 > 0:12:09Flat land is scarce,
0:12:09 > 0:12:12so these fields have been painstakingly carved out
0:12:12 > 0:12:15of the foothills and water guided in.
0:12:25 > 0:12:30These man-made marshlands, perched on the edge of the mountains,
0:12:30 > 0:12:32are a magnet for wildlife.
0:12:41 > 0:12:44At the start of summer, as soon as the rice is planted,
0:12:44 > 0:12:46mysterious white globes start to appear
0:12:46 > 0:12:49in the trees around the paddy fields.
0:12:54 > 0:12:57The paddy fields can be a dangerous place to raise your young.
0:12:58 > 0:13:00Hungry mouths are everywhere.
0:13:07 > 0:13:10So some mothers have taken to the trees
0:13:10 > 0:13:13to give their babies a fighting chance of survival.
0:13:13 > 0:13:15FROGS CROAK
0:13:18 > 0:13:23The white globes are being made by these Japanese tree frogs.
0:13:29 > 0:13:31It's the breeding season
0:13:31 > 0:13:34and the trees are teeming with frogs.
0:13:35 > 0:13:38The female is with a male at the tip of a branch,
0:13:38 > 0:13:40perched above the paddy pool.
0:13:41 > 0:13:44She's building a nest by whipping up a giant ball of foam
0:13:44 > 0:13:45with her back legs.
0:13:47 > 0:13:50She lays hundreds of eggs inside.
0:13:53 > 0:13:56She's attracting the attention of other males.
0:13:59 > 0:14:03Each male could still fertilise some of the remaining eggs in the foam.
0:14:05 > 0:14:08They're coming in from all directions.
0:14:15 > 0:14:19But the foam makes it hard to get to grips with the competition.
0:14:27 > 0:14:31Things quickly descend into an undignified wrestling match.
0:14:59 > 0:15:02This male's work is done here.
0:15:02 > 0:15:04It's time to move on and find other nests.
0:15:06 > 0:15:09But when you're covered in slippery foam,
0:15:09 > 0:15:11it's hard to leave with dignity.
0:15:23 > 0:15:26It's an unusual problem for a tree frog.
0:15:38 > 0:15:40As the days pass,
0:15:40 > 0:15:43the eggs develop in the safety of their foam nest.
0:15:45 > 0:15:47The temperature rises with the summer sun,
0:15:47 > 0:15:51and the foam ball dries to form a protective case.
0:15:53 > 0:15:57The tadpoles inside are still moist,
0:15:57 > 0:15:59and six degrees cooler.
0:16:04 > 0:16:06But the little tadpoles need rain.
0:16:09 > 0:16:10At this time of year,
0:16:10 > 0:16:14warm air is rising over the steep Honshu mountains
0:16:14 > 0:16:17and clouds are starting to build.
0:16:24 > 0:16:28The tree frogs have timed their nest-building perfectly.
0:16:32 > 0:16:37After 20 days, conditions are just right
0:16:37 > 0:16:39and the waiting is over.
0:16:44 > 0:16:49The hard foam starts to dissolve and the tadpoles drop out,
0:16:49 > 0:16:53straight into the nursery pool of the rice paddy below.
0:17:16 > 0:17:20They feast on the remaining pieces of the nest -
0:17:20 > 0:17:24a final meal before they take their chances in the big, wide world.
0:17:25 > 0:17:29Their mother has pulled off a remarkable feat of planning.
0:17:38 > 0:17:42Over a third of Japan's fresh water goes to its paddies.
0:17:43 > 0:17:46Everyone relies on this precious resource
0:17:46 > 0:17:50and there are some uniquely Japanese ways of keeping it pure.
0:18:05 > 0:18:09The little village of Harie has a network of interconnecting canals.
0:18:11 > 0:18:14But these are not just any streams,
0:18:14 > 0:18:18they're part of an ancient system called kabata.
0:18:28 > 0:18:32The water is piped into small buildings close to each house.
0:18:37 > 0:18:40This is where Mrs Fukuda prepares her vegetables
0:18:40 > 0:18:42and does her washing up.
0:18:46 > 0:18:49All this waste should make the water dirty
0:18:49 > 0:18:51but it's not.
0:18:51 > 0:18:53It stays sparklingly clear.
0:18:55 > 0:18:57That's because Mrs Fukuda
0:18:57 > 0:18:59has an unusual band of kitchen helpers.
0:19:01 > 0:19:02Giant carp.
0:19:11 > 0:19:15As she washes her food and plates, the carp move in.
0:19:29 > 0:19:32Carp are natural ground feeders,
0:19:32 > 0:19:35sucking up the crumbs that sink to the bottom.
0:19:41 > 0:19:44As Mrs Fukuda rinses out her rice bowls,
0:19:44 > 0:19:46the carp pick out the bits of food
0:19:46 > 0:19:48and clean the water at the same time.
0:19:53 > 0:19:56No detergents, no waste,
0:19:56 > 0:19:59just some very obliging, well-fed fish.
0:20:10 > 0:20:14The same water is now piped out of the kitchen and on to the crops,
0:20:14 > 0:20:18clean and clear, for the benefit of everyone on the lowlands.
0:20:21 > 0:20:24They call this place 'the village of living water'.
0:20:26 > 0:20:29And around the edges of these waterways, on summer nights,
0:20:29 > 0:20:32something enchanting happens.
0:20:38 > 0:20:42As darkness falls, the air is filled with tiny lights.
0:20:47 > 0:20:48Fireflies.
0:20:48 > 0:20:52They can only thrive if their watery world is pristine.
0:20:53 > 0:20:56They've spent most of their brief lives as larvae,
0:20:56 > 0:20:58living in river beds.
0:20:58 > 0:21:00But for just a few weeks in summer,
0:21:00 > 0:21:03they emerge as adults to find partners.
0:21:05 > 0:21:08The female flashes her abdomen to attract attention.
0:21:13 > 0:21:15Soon, she's surrounded by eager males,
0:21:15 > 0:21:18all synchronising their flashes with hers.
0:21:23 > 0:21:27People call this dancing swarm a firefly contest.
0:21:38 > 0:21:42They've caught the imagination of countless generations.
0:21:51 > 0:21:55People once thought they were the fire of human souls,
0:21:55 > 0:21:56floating in the night.
0:22:21 > 0:22:23The female has found her mate.
0:22:24 > 0:22:27It will be a brief relationship.
0:22:29 > 0:22:31In a few weeks, they'll all be gone.
0:22:31 > 0:22:35But the pure water has created a magical, fleeting encounter
0:22:35 > 0:22:38between people and wildlife.
0:22:45 > 0:22:48There's a strong spiritual connection with nature
0:22:48 > 0:22:50in these mountain heartlands.
0:22:58 > 0:23:02Over half of Honshu is still thickly forested...
0:23:03 > 0:23:05..and people believe the oldest trees
0:23:05 > 0:23:08are inhabited by kodama -
0:23:08 > 0:23:09tree-spirits.
0:23:11 > 0:23:13The forests echo with their voices.
0:23:13 > 0:23:16LOUD HOWLS AND SCREECHES
0:23:21 > 0:23:26It's bad luck, so they say, to cut down a tree where a kodama lives.
0:23:41 > 0:23:44But there's another elusive creature in these ancient forests
0:23:44 > 0:23:47that was once hunted almost to extinction.
0:23:50 > 0:23:54People call it the cow demon or the phantom.
0:23:59 > 0:24:01It's a Japanese serow.
0:24:02 > 0:24:06This relative of antelopes and goats is unique to Japan.
0:24:08 > 0:24:10It's a strange, stocky creature,
0:24:10 > 0:24:13but it has a certain quirky charisma.
0:24:18 > 0:24:20When numbers fell dangerously low,
0:24:20 > 0:24:23the Japanese government banned hunting.
0:24:26 > 0:24:31The serow was saved and it's become an unlikely national icon.
0:24:33 > 0:24:35But it's a hard one to get to know.
0:24:39 > 0:24:43At the slightest hint of danger, it will vanish into the forest...
0:24:44 > 0:24:45..like a ninja.
0:24:58 > 0:25:00These are still wild woods.
0:25:01 > 0:25:05But as you leave the foothills, the land flattens
0:25:05 > 0:25:08and it becomes easier for people to settle.
0:25:14 > 0:25:17It's when animals leave the forest edge and move into farmland
0:25:17 > 0:25:21that the relationship with humans becomes less benevolent.
0:25:30 > 0:25:32The macaques of the lower forests
0:25:32 > 0:25:35are as bold as their mountain cousins
0:25:35 > 0:25:38and often venture out in search of new opportunities.
0:25:38 > 0:25:40CAR HORN HONKS
0:25:42 > 0:25:44There are all sorts of perils,
0:25:44 > 0:25:48but there are rewards too, if you're willing to take some risks.
0:25:49 > 0:25:51CAR HORN HONKS
0:25:56 > 0:25:59For over 100 years, people have been growing
0:25:59 > 0:26:02the finest fruit and vegetables on these warm, rich soils.
0:26:09 > 0:26:11For these cheeky thieves, it's irresistible.
0:26:29 > 0:26:33Growing perfect produce is a Japanese obsession
0:26:33 > 0:26:36so the last thing people want is marauding macaques.
0:26:46 > 0:26:49As the day heats up, the farmers take a break.
0:27:11 > 0:27:13The coast is clear.
0:27:20 > 0:27:22They have to be cautious.
0:27:22 > 0:27:25If they're spotted, there'll be trouble.
0:27:33 > 0:27:37But every day they brave the electric fences.
0:27:37 > 0:27:42They know all the weak spots where they can stage their raids.
0:27:47 > 0:27:51And they gorge themselves on the fruit of the farmers' labours.
0:28:05 > 0:28:09They are almost impossible to stop
0:28:09 > 0:28:12but the farmers are not prepared to give in.
0:28:14 > 0:28:16DOG BARKS
0:28:17 > 0:28:20They bring out their secret weapon.
0:28:22 > 0:28:24Specially-trained monkey dogs.
0:28:24 > 0:28:26DOG GROWLS
0:28:39 > 0:28:43The Japanese Shiba Inu is one of the world's oldest breeds
0:28:43 > 0:28:47and people have trained them to protect their crops against monkeys.
0:28:47 > 0:28:50There's even a Japanese saying that when people are fighting,
0:28:50 > 0:28:52they're like a dog and a monkey.
0:28:58 > 0:29:01But the rewards outweigh the risks.
0:29:01 > 0:29:02They'll be back again tomorrow.
0:29:15 > 0:29:17But fruit farmers aren't the only ones
0:29:17 > 0:29:19having to outwit hungry visitors.
0:29:37 > 0:29:42Mr Nakayama has been keeping honeybees for more than 65 years
0:29:42 > 0:29:46and these sunny forest clearings are perfect for his hives.
0:29:54 > 0:29:58But every year, Mr Nakayama's hives come under attack.
0:30:02 > 0:30:07Whatever it is seems to be unfazed by a swarm of angry bees.
0:30:12 > 0:30:17Mr Nakayama has put an electric fence around his precious hives
0:30:17 > 0:30:21but even this doesn't seem to be keeping the culprit out.
0:30:25 > 0:30:27So he's called in some experts
0:30:27 > 0:30:30and they've set up an elaborate trap laden with honey.
0:30:47 > 0:30:49All they can do now is wait.
0:30:56 > 0:30:59And it doesn't take long.
0:30:59 > 0:31:04Within just a few hours, news comes in that the trap's been tripped.
0:31:05 > 0:31:06GROWLING
0:31:13 > 0:31:17Professor Izumiyama and his team are here to help.
0:31:19 > 0:31:21Although it's wise to tranquillise it first.
0:31:29 > 0:31:31It's a young black bear.
0:31:33 > 0:31:37He's strayed dangerously close to the edge of human habitation,
0:31:37 > 0:31:39looking for something to eat.
0:31:41 > 0:31:45Black bears have attacked people in the past
0:31:45 > 0:31:48so, for everyone's sake, he can't stay here.
0:31:56 > 0:31:59There's just enough room for the bear in the boot.
0:32:03 > 0:32:07He needs to be returned to the safety of the mountain
0:32:07 > 0:32:10but it's a one-hour drive.
0:32:12 > 0:32:14The bear could awake at any time.
0:32:15 > 0:32:17And there's no cage!
0:32:19 > 0:32:21In this rural area,
0:32:21 > 0:32:25bear expert Professor Izumiyama is used to taking this chance.
0:32:34 > 0:32:36They need to take the bear
0:32:36 > 0:32:39as deep into the mountain wilderness as possible.
0:33:09 > 0:33:12This is the most anxious time for the professor.
0:33:26 > 0:33:30Thanks to Professor Izumiyama, this lucky bear
0:33:30 > 0:33:33is back in the safety of the forest and out of harm's way.
0:33:44 > 0:33:48All across Honshu, big towns have grown up along the forest edges.
0:33:50 > 0:33:53Some are more than 1,000 years old.
0:33:55 > 0:34:00Here, links with nature are rooted in the most ancient beliefs.
0:34:03 > 0:34:06These sika deer live in the hills around Nara,
0:34:06 > 0:34:08one of the oldest towns in Japan.
0:34:12 > 0:34:15But, every morning, they leave the safety of the forest
0:34:15 > 0:34:17and head straight into town.
0:34:27 > 0:34:31Their destination is one of the most sacred places in Japan.
0:34:36 > 0:34:39The temple is the world's largest wooden building.
0:34:39 > 0:34:43Large enough to house a 15-metre statue of Buddha.
0:34:44 > 0:34:47It's visited by thousands of pilgrims.
0:34:56 > 0:34:58The deer are allowed in
0:34:58 > 0:35:01because they're believed to be messengers of the gods.
0:35:06 > 0:35:08No-one is allowed to harm them.
0:35:14 > 0:35:17Legend has it that a god arrived at the shrine of Nara
0:35:17 > 0:35:20riding on the back of a deer.
0:35:20 > 0:35:251,200 years later, the deer are still regarded as sacred.
0:35:41 > 0:35:44They've become local celebrities.
0:35:53 > 0:35:56And they take full advantage of the situation.
0:35:59 > 0:36:02150 yen buys you a bag of deer biscuits.
0:36:06 > 0:36:09For many people visiting the temple,
0:36:09 > 0:36:12this may be as close to wildlife as they will ever get.
0:36:14 > 0:36:17But the relationship clearly needs some finessing.
0:36:28 > 0:36:33Some of the deer take unfair advantage of their sacred status.
0:36:33 > 0:36:34LAUGHTER
0:36:38 > 0:36:40As with all things in Japan,
0:36:40 > 0:36:43courtesy and respect goes a long way.
0:36:48 > 0:36:52A simple bow is quickly rewarded and everyone is happy.
0:37:29 > 0:37:31When they've had enough biscuits,
0:37:31 > 0:37:34the Nara deer head back to their home in the forest.
0:37:42 > 0:37:46But as you travel further from these mountain fringes,
0:37:46 > 0:37:50the landscape of Honshu is swallowed up in an urban sprawl.
0:37:53 > 0:37:56Every inch of the remaining flat land to the coast
0:37:56 > 0:37:59has been taken over by people.
0:38:02 > 0:38:08Over 35 million people are crammed into an area smaller than Yorkshire.
0:38:22 > 0:38:25In this concrete landscape,
0:38:25 > 0:38:28it would seem unlikely that any wildlife could survive.
0:38:32 > 0:38:36But one animal has made the city its home
0:38:36 > 0:38:40and it has a strangely charmed reputation.
0:38:41 > 0:38:46People even put fat little statues of it outside bars and restaurants.
0:38:48 > 0:38:52It's naughty, but it's also believed to bring good luck.
0:38:59 > 0:39:01Tanuki - the raccoon dog.
0:39:06 > 0:39:08It's a creature of the forest
0:39:08 > 0:39:12but, as buildings have replaced trees, it's been forced to adapt.
0:39:13 > 0:39:16These little creatures will eat almost anything.
0:39:19 > 0:39:21There's an opportunity at every turn.
0:39:31 > 0:39:34Tanuki make mischievous neighbours.
0:39:34 > 0:39:37But people think they're lucky, so they get away with it.
0:39:41 > 0:39:45They're so comfortable with urban life, they never leave.
0:39:50 > 0:39:52TANUKI CUBS SQUEAL AND CHITTER
0:40:03 > 0:40:07This mum is raising her brood next to a busy railway line,
0:40:07 > 0:40:10which could be lethal for cubs newly out of the den,
0:40:10 > 0:40:13but they grow up fast and quickly become streetwise.
0:40:15 > 0:40:17TRAIN BLASTS HORN
0:40:25 > 0:40:28Maybe they deserve that lucky reputation.
0:40:35 > 0:40:37All across this crowded island,
0:40:37 > 0:40:41people and nature are thrown closer together.
0:40:48 > 0:40:52In Japan's ancient Buddhist and Shinto philosophy,
0:40:52 > 0:40:56harmony with nature is an essential part of life.
0:41:02 > 0:41:04Mr Watanabe is hard at work.
0:41:15 > 0:41:18The space he is tending is called karesansui -
0:41:18 > 0:41:21dry mountain and water.
0:41:39 > 0:41:42Mr Watanabe has transformed Honshu's great mountains
0:41:42 > 0:41:46and raging torrents into something beautifully simple.
0:41:50 > 0:41:53It's nature in its purest essence,
0:41:53 > 0:41:56for people to observe and reflect on.
0:42:11 > 0:42:16But this is a land where the forces of nature are impossible to tame.
0:42:17 > 0:42:19WATER GUSHES LOUDLY
0:42:21 > 0:42:25Honshu sits at the mercy of four slabs of the earth's crust.
0:42:26 > 0:42:30Every year, there are nearly 5,000 earthquakes and tremors.
0:42:31 > 0:42:35The rocks steam and hiss with sulphurous gases.
0:42:35 > 0:42:40It's no wonder the Japanese call these areas Jigokudani -
0:42:40 > 0:42:41Hell Valley.
0:42:46 > 0:42:49No-one is far from an active volcano.
0:42:51 > 0:42:55Mount Fuji is just 60 miles from Tokyo.
0:42:57 > 0:43:01This volatile landscape continues all the way to the coast.
0:43:06 > 0:43:10These cliffs at Sanriku were pushed 200 metres above the sea
0:43:10 > 0:43:13by violent upheavals under the ocean floor.
0:43:13 > 0:43:16WAVES CRASH LOUDLY
0:43:22 > 0:43:27This eastern coastline is regularly battered by tsunamis.
0:43:44 > 0:43:46On the west coast of Honshu,
0:43:46 > 0:43:51geological forces have formed a vast trench that runs just offshore.
0:43:52 > 0:43:57But here, this extreme landscape creates a rare moment of magic.
0:44:01 > 0:44:05An underwater valley, nearly 2,000 metres deep, runs close to shore.
0:44:11 > 0:44:14The local fishermen are so in tune with nature,
0:44:14 > 0:44:17they know exactly when conditions are right
0:44:17 > 0:44:19to cast their nets above the deep valley.
0:44:26 > 0:44:28ENGINES WHIR
0:44:31 > 0:44:33GULLS SQUAWK
0:44:35 > 0:44:38Something is stirring far below the boats.
0:44:43 > 0:44:45These are firefly squid.
0:44:51 > 0:44:56They spend most of their lives 300 metres down in the ocean depths,
0:44:56 > 0:44:59signalling to each other in the darkness
0:44:59 > 0:45:01using bioluminescent chemicals in their skin.
0:45:07 > 0:45:11But on spring nights, the currents carry them up to the shallows,
0:45:11 > 0:45:13where they mate and spawn.
0:45:16 > 0:45:19As the eggs float back to the depths,
0:45:19 > 0:45:22the squid's lifecycle comes to its natural end.
0:45:29 > 0:45:32The fishermen have waited months for this brief event.
0:45:36 > 0:45:38The squid are barely eight centimetres long
0:45:38 > 0:45:40but there are millions of them.
0:45:44 > 0:45:47It's a valuable catch of sushi.
0:45:48 > 0:45:50GULLS SQUAWK WILDLY
0:46:02 > 0:46:07As the fishermen haul in their nets, they may see something even rarer.
0:46:13 > 0:46:16For just a few nights of the year,
0:46:16 > 0:46:19if the moon, the tide and the wind are aligned,
0:46:19 > 0:46:22the dying firefly squid are swept ashore.
0:46:25 > 0:46:29It's the last, dazzling moment of their lives.
0:46:58 > 0:47:01Between the turbulent sea and the inhospitable mountains,
0:47:01 > 0:47:04there may be little room left to live,
0:47:04 > 0:47:07but nature is still appreciated by millions of people.
0:47:22 > 0:47:24Late at night in Tokyo,
0:47:24 > 0:47:28the cherry blossom celebrations are ending with a great party.
0:47:31 > 0:47:34Hanami, or blossom-viewing parties,
0:47:34 > 0:47:37have been held here for more than 1,000 years.
0:47:37 > 0:47:41People gather under the trees to eat traditional food,
0:47:41 > 0:47:43helped along with some sake.
0:47:49 > 0:47:52But there's a poignancy to all this revelry.
0:47:54 > 0:47:59Cherry blossom only appears for a brief moment in spring.
0:47:59 > 0:48:02Within just a few days, it will all have fallen.
0:48:07 > 0:48:12The delicacy of the flowers captures a particularly Japanese sentiment...
0:48:13 > 0:48:15..the spirit of "mono no aware".
0:48:18 > 0:48:21It's a wistful understanding of the transience of life.
0:48:25 > 0:48:30All this will come to an end and it must be appreciated in the moment.
0:48:32 > 0:48:36It perfectly captures the Japanese connection
0:48:36 > 0:48:38to the natural world.
0:48:42 > 0:48:44In such a crowded island,
0:48:44 > 0:48:48people and nature must find ways to live together.
0:48:52 > 0:48:55But all across Honshu,
0:48:55 > 0:48:58there's an ancient bond with the natural world
0:48:58 > 0:49:00that still runs deep.
0:49:17 > 0:49:21There aren't many places in the world where the lives of people
0:49:21 > 0:49:24and animals cross so closely as on Honshu.
0:49:24 > 0:49:28Here, there are two animals that can cause havoc.
0:49:29 > 0:49:32Japanese macaques and black bears.
0:49:34 > 0:49:35This is a front line,
0:49:35 > 0:49:39where these two animals are always in conflict with people,
0:49:39 > 0:49:42so that makes it a challenging story to tell.
0:49:42 > 0:49:44OK and go ahead.
0:49:44 > 0:49:47Cameraman John Brown has filmed these interactions before
0:49:47 > 0:49:50and knows how tricky they are.
0:49:50 > 0:49:52OK, I think probably this end, I would say.
0:49:52 > 0:49:53SHE SPEAKS IN JAPANESE
0:49:53 > 0:49:57But the team are working with some extraordinary and passionate people.
0:49:57 > 0:49:59OK. I think we should...
0:50:00 > 0:50:04Professor Shigeyuki Izumiyama is a bear biologist
0:50:04 > 0:50:07and he knows this area very well.
0:50:07 > 0:50:11He's spent the last 25 years rescuing and relocating black bears
0:50:11 > 0:50:14that have strayed too close to human habitation.
0:50:15 > 0:50:19Professor Izumiyama is an incredible individual.
0:50:19 > 0:50:23He's a brilliant biologist that really understands his animals.
0:50:23 > 0:50:26He's the only individual, as far as I know,
0:50:26 > 0:50:29who's trying to tackle this problem.
0:50:51 > 0:50:54The film crew are keen to film him catching a bear.
0:50:55 > 0:51:00As soon as the next trap is sprung, he'll give them a call.
0:51:03 > 0:51:06Meanwhile, the team are trying to film the other problem animal -
0:51:06 > 0:51:09the macaques that raid the farmlands.
0:51:09 > 0:51:12Filming macaques crop-raiding is a huge challenge
0:51:12 > 0:51:16because they see any human presence as a major threat,
0:51:16 > 0:51:21so they'll run as soon as they sense that they have been noticed.
0:51:21 > 0:51:23So I guess the important thing is to kind of get a sense
0:51:23 > 0:51:26of which direction they're going, if they're coming down...
0:51:26 > 0:51:30They are being helped by scientist Takayo Soma.
0:51:30 > 0:51:34She grew up round here, so she knows the situation very well.
0:51:34 > 0:51:36Finding macaques is easy,
0:51:36 > 0:51:39but the team want to film their crop-raiding behaviour.
0:51:39 > 0:51:42That's not so straightforward.
0:51:44 > 0:51:46EXPLOSION
0:51:49 > 0:51:52The farmers are keen to move the macaques on
0:51:52 > 0:51:54and they use firecrackers and dogs to scare them away.
0:51:54 > 0:51:57DOG BARKS
0:52:00 > 0:52:04The macaques cause £5 million worth of damage every year,
0:52:04 > 0:52:06so it's understandable.
0:52:08 > 0:52:12It's such a big issue, there's even a monkey policeman on patrol.
0:52:16 > 0:52:18I think he's following us now.
0:52:18 > 0:52:20I think he knows we're onto something.
0:52:20 > 0:52:23The crew just need a bit of time to film,
0:52:23 > 0:52:25so Takayo goes to negotiate.
0:52:26 > 0:52:28She has a trick up her sleeve.
0:52:32 > 0:52:34SHE LAUGHS
0:52:34 > 0:52:37- You bribed him with an Oreo? - You gave him some biscuits?
0:52:37 > 0:52:40- He gave you a biscuit? - I had biscuit.
0:52:40 > 0:52:43- That's genius.- How many bites? He just took one bite.
0:52:43 > 0:52:44- Two bites.- Two bites?!
0:52:44 > 0:52:48- That's a brilliant bit of work. - Wow, he's got a pretty low price.
0:52:50 > 0:52:52But just as the coast is clear,
0:52:52 > 0:52:56director Gavin Maxwell gets a call from Professor Izumiyama.
0:52:59 > 0:53:02The previous night, up in the forest,
0:53:02 > 0:53:04a bear wandered into one of the traps.
0:53:06 > 0:53:09The bear was caught last night
0:53:09 > 0:53:12and we're going as fast as we can to get to this site now.
0:53:12 > 0:53:14It's about 45 minutes away.
0:53:14 > 0:53:17So we're in a bit of a race to get there in time.
0:53:24 > 0:53:26LOUD CLATTERING
0:53:27 > 0:53:28Big bear in there.
0:53:34 > 0:53:36As well as relocating bears,
0:53:36 > 0:53:40Professor Izumiyama also studies them.
0:53:50 > 0:53:53By fitting radio collars to track them,
0:53:53 > 0:53:55he hopes to discover more about their movements.
0:53:56 > 0:53:59I'm not sure how much more time we've got.
0:54:01 > 0:54:04They have to work fast, before the drugs wear off.
0:54:21 > 0:54:22(Does the bear have a name?)
0:54:28 > 0:54:30- Hirokun.- Hirokun.
0:54:30 > 0:54:32- Hirokun.- Hirokun.
0:54:33 > 0:54:38As Hirokun begins to stir, it's wise to take some precautions.
0:54:38 > 0:54:41Just John and Izumiyama-san we'll leave here.
0:54:41 > 0:54:44- So we should retreat to the inside of the car?- Yeah.
0:54:51 > 0:54:54Professor Izumiyama carries pepper spray
0:54:54 > 0:54:56just in case of attack.
0:54:57 > 0:55:01John knows how nervous local people can get.
0:55:01 > 0:55:04People get so scared and so angry about these bears
0:55:04 > 0:55:07that unless he did something, they'd just end up dead.
0:55:07 > 0:55:10A few hours of unpleasantness, which it will have forgotten by tomorrow,
0:55:10 > 0:55:12is well worth it.
0:55:16 > 0:55:20Another bear on its way, but now its movements can be tracked.
0:55:20 > 0:55:23- Hunter.- Yeah, that one. - If, maybe in a weeks' time...
0:55:23 > 0:55:28Over 25 years, Professor Izumiyama has caught a lot of bears.
0:55:28 > 0:55:30- More than 1,000. - More than 1,000 bears.
0:55:30 > 0:55:32THEY LAUGH
0:55:32 > 0:55:371,000 bears and counting and there's no sign of stopping yet.
0:55:37 > 0:55:41As soon as one bear is released, it's straight on to another.
0:55:42 > 0:55:46Throughout the summer, he's on call 24/7.
0:55:49 > 0:55:51Despite being such a populated country,
0:55:51 > 0:55:55Honshu is home to over 10,000 bears...
0:55:55 > 0:55:56TRACKER PINGS
0:55:56 > 0:56:00..and what Professor Izumiyama is discovering is remarkable.
0:56:01 > 0:56:05These bears have huge territories.
0:56:05 > 0:56:08They can roam nearly 50 square miles in search of food.
0:56:10 > 0:56:13All this effort will help to keep bears away from people
0:56:13 > 0:56:15so that both stay safe.
0:56:20 > 0:56:23The next day, the team are back on the plains,
0:56:23 > 0:56:26still trying to catch the macaques staging a crop-raid.
0:56:26 > 0:56:28We haven't seen anything.
0:56:33 > 0:56:36- Anything interesting?- No.
0:56:37 > 0:56:39But with Takayo's expert help,
0:56:39 > 0:56:42they are learning to predict the macaques' movements.
0:56:45 > 0:56:49You might spot a macaque or two who are, kind of, looking a bit shifty
0:56:49 > 0:56:53and you kind of get the sense that something's going to happen.
0:56:53 > 0:56:55And then, at last,
0:56:55 > 0:56:58they are in the right place at the right time for a raid.
0:57:08 > 0:57:10Is that an apple in his hand?
0:57:12 > 0:57:14Caught red-handed.
0:57:18 > 0:57:22In a place with such close proximity between people and animals,
0:57:22 > 0:57:25the relationship is always going to be challenging.
0:57:26 > 0:57:29But Professor Izumiyama has seen a big change in attitudes
0:57:29 > 0:57:32since he first started working with bears.
0:58:13 > 0:58:16Next time, we head to Japan's far south.
0:58:19 > 0:58:22This is a land ruled by the power of the sea.
0:58:25 > 0:58:29Here, you have to make the most of every opportunity.
0:58:30 > 0:58:35And the further south you travel, the stranger life becomes.