Japan's Strangest Unsolved Mystery

(eerie music) (static crackling) (suspenseful music) (static crackling) - Monday. (foreboding music) (animals calling) The peak is shrouded in fog. It's the aftermath of one of the most violent storms to hit the area in months.

A search helicopter powers through the mist, scouring the region for a pair of hikers from Tokyo who set out the day prior and haven't been seen or heard from since. This hunt has been ongoing for hours, sunlight dwindling as search teams comb every crevice, yet find no trace of anyone around. But as nightfall takes its grip, enveloping the area in complete blackness, suddenly something strange enters their view.

(thunder crashes) Just south of Mount Asahi-dake, a crudely constructed, massive SOS sign beckons from a clearing. It's undeniable that the missing hikers have made this, and it's a damn good thing they did, because with conditions like these, finding them otherwise would've been nearly impossible. (helicopters chopping) (foreboding music) The team swarms the area with newfound hope that these hikers just might be hiding nearby.

They search, and search, and search until, finally, (tense music) they find them. (helicopters chopping) About a mile north, the two men emerge from a cave. They are completely disoriented, battered, and exhausted, but most prominently are in complete disbelief that the rescuers found them.

As they're pulled up into the aircraft, the search team reassures them that they're gonna be okay before commending them on their efforts while out there. "We couldn't have found you without your help," they claim. "You guys did a really great job building that sign.

" The men pause for a minute, visibly confused. "I'm sorry. We didn't build a sign.

We have no idea what you're talking about. " (foreboding music) (air whooshing) (rain pattering) (screen whooshes) (mysterious music) You know, I'll admit, the island of Hokkaido is beautiful. It's a landscape adorned with volcanic mountaintops, trails with serene views, and a multitude of steam vents giving the area an almost dreamlike aesthetic.

It's no wonder that it's one of the most popular hiking spots in Japan, as no matter what time of year you go, you're bound to have an experience you'll never forget. (mysterious music) From the summit of Mount Asahi-dake, it was 2. 6 miles directly south where the SOS sign awaited.

(air whooshes) Resting in a relatively flat wetland, it was constructed with 19 cleanly cut birch tree logs, each measuring at around 16 feet long. (mysterious music) Interestingly, the deviation down here is considerably longer than the main hiking trail on the mountain, making its existence entirely perplexing. As far as it's known, there are no trails south of this mountain, implying that whoever built it had to have made their diversion from the north, a detour littered with steep cliffs, a dense forest, and even the turbulent Chubetsu River.

At this point, it's completely unknown how this person got here, and for Japanese police, it was undeniable that a mystery was brewing on the mountain. Someone is still out there, likely pleading for help. (tense music) (wind whooshing) (eerie music) One day later, a second team is dispatched to probe the area for any signs of hikers in distress, this time with emphasis on the wetland the sign sits in.

And while they all held out hope of finding someone still alive, unfortunately, just a few short hours into their search, they'd uncover quite the contrary. (eerie music) Hidden near the SOS sign are scattered human remains covered in bite marks from wildlife, and nearby, (tense music) a backpack containing various items: (bright music) a Sony Walkman, four cassette tapes, toothpaste, a bar of soap, and a towel. At first glance, it's obvious that the belongings and the human bones are connected.

However, a curious question lingered in everyone's mind. How did this person with enough energy and strength to build an SOS sign out of 19 massive logs allow themselves to die in nature? For the rescue team, nothing further was discovered that day.

For what it's worth, though, this seemed like a pretty open and shut case. Locals have claimed that the weather on this mountain is volatile, with thunderstorms rolling in with hardly any notice. Perhaps this person got turned around, mistakenly made their way down here, and spent their final days awaiting help that never came.

(thunder rumbles) (mysterious music) The site at the SOS sign and the story it tells is grim. But all things considered, this case, again, seemed relatively straightforward. Someone passed away here and built an SOS sign before it happened.

The only question really was who was it, and how exactly did they get here? (wind whooshing) (eerie music) (screen whooshes) (foreboding music) Two days pass, and examiners from the Asahikawa Medical University notify Hokkaido police that the human bones belong to a female. (bright music) Reportedly, she was about 5'3" tall, had Type O blood, was somewhere between 20 and 40 years old at the time of her death, carried bone fractures in multiple locations, and died within the span of one to three years prior.

Aside from this, there was no further identifying information about her, and effectively, (interference buzzes) she was cons, cons, cons, (foreboding music) sh, sh, sh, sh, sh, sh, sh. (foreboding music) (bright music) (foreboding music) Something is wrong. (foreboding music) This doesn't make any sense at all.

(foreboding music) Upon calculating the weight of the SOS logs by utilizing numerous wood weight charts online, I found that 16 foot segments of birch wood weighs anywhere between 150 and 400 pounds each, depending on diameter. Multiply this by the 19 segments this sign is comprised of, and we have a whopping total range of 2,850 and 7,600 pounds of total weight making up this sign. So with this information, we're left to assume that a 5'3" female with fractured bones had the energy and strength to not only cut down 19 massive trees with tools that were never found, but also had the stamina to transport anywhere between one and three tons of weight completely by herself.

Let's not forget either that all of this was done after taking a treacherous 2. 6 mile diversion down the south side of the mountain, undoubtedly causing considerable exhaustion from the elements. Without help, constructing this sign alone is an extraordinary feat, a feat that doesn't add up given the context here.

So was this person actually alone, or was there perhaps someone else that died there with her? (suspenseful music) (machine clicks) (static crackling) (cheerful jaunty music) All right, guys, before we continue down the rabbit hole, I'd like to tell you about tonight's video sponsor, Incogni. All right, so it seems like nearly every year now I read about yet another data breach.

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(suspenseful music) (foreboding music) (wind whooshing) It's late at HQ, and investigators are scouring for clues. Of everything they uncovered, the cassette tapes seem to be the most promising lead on uncovering the identity of this woman. And so they put them in their tape player and begin to listen.

As they play, they're met with musical tracks taken from various anime TV shows. However, once they make it to the last one, something strange gives them pause. (foreboding music) (static hissing) (machine whirring) (upbeat jaunty music) (vocalist singing in Japanese) (music stops) (SOS voice shouting in Japanese) (machine clicks) - [Nexpo] Despite the bones being female, the voice on this recording, clearly in distress, belongs to a man.

And the translation? (bright music) "SOS, help me. I'm stuck on the cliff.

SOS, help me. I'm at the location where I first met the helicopter. The sasa is deep, and I can't climb up.

Please, pick me up here. " Interesting. (mysterious music) (foreboding music) Aside from the blatant parallels to the SOS sign, I can't help but find it strange that this man uses not a single phrase implying that he's with someone.

I don't know about you, but if I were stranded somewhere with another person, I'd plead for someone to help us because we are the ones stuck here. In this recording, though, it sounds as if he's completely alone, unaware that a female is stranded in the exact same area, almost like, to him, this female doesn't exist. The woman who the bones belong to and the man who the voice belongs to almost exist in a vacuum, remnants of two people discovered in the exact same spot, completely unaware of the other's existence.

The only thing tying them together, an SOS sign nearly impossible for one person to build and whispers of an agonizing death. A site of demise that we are years too late with uncovering. (mysterious music) (wind whooshing) (foreboding music) (wind whooshing) (mysterious music) Fascinated by this case, a Japanese reporter named Koyo Aburatani sets out to the site of the SOS sign in search of any clues the police may have overlooked.

While uncovering anything new was one hell of a long shot, surprisingly, after they dug through some tree roots, (object scrapes and thuds) they actually uncovered something. Just 165 feet north of the SOS sign, and hidden under foliage, was a large hole containing various belongings: (bright music) two cameras, a notebook, and most, prominently, (bright music) a license. This ID belonged to a man named Kenji Iwamura, someone from Konan City in Southern Japan, over 800 miles south.

(foreboding music) This discovery was massive because, for all anyone knew, this was bound to be their guy. I mean, this had to have been the voice on the recording, right? And of course, this man must have been associated in some capacity with the female bones found at the same site.

While she may be, up to this point, still unidentified, at the very least, those investigating this case finally had a name, Kenji Iwamura. (machine clicks) (machine whirring) (foreboding music) (machine clicks) (machine whirring) (foreboding music) It's the middle of summer, and 24-year-old Kenji Iwamura sets out for Mount Asahi-dake for a short hiking trip. He arrives at a small mountain lodge at the base of the summit, and only plans to be there for a couple nights.

Later on, he informs the hotel owner that he's embarking on a hike, ignoring warnings of a storm that would hit the area that night. Hesitant, the owner agrees, and so Kenji sets off from the hotel lobby and embarks into the great unknown. (mysterious music) (screen whooshes) (clock ticking) As time ticks by, the sky darkens, the hotel owner becoming increasingly anxious, and with no way to contact him to confirm how he's faring in this unstable weather.

Hours pass without a word from him. The storm comes and goes. The clock approaches.

(bell clangs) Days pass without a word from him. Weeks come and go. Kenji Iwamura never turned up.

(eerie music) He was never seen again. (eerie music) With the discovery of Kenji's ID, police were certain that they'd cracked this case. Reportedly, determining gender from bone fragments isn't always accurate, and for all they knew, they had to belong to him.

From here, they tracked down and contacted Kenji's family, believing that this was the final piece of verification they needed to close this case. Their confidence was at an all-time high, catalyzed by his parents later claiming that he was an avid fan of anime and that the backpack they uncovered indeed belonged to him. And so, at last, the police play the cassette tape for them, certain that they'd recognize the voice of their son.

And as fate would have it, by the grace of God, (suspenseful music) they didn't recognize this voice at all. They have no idea who this person is. (foreboding music) With no evidence of foul play, Hokkaido police bizarrely continued to run with their theory that this sign was built by Kenji Iwamura.

They cast aside the consensus about the bones, the lack of identification with the voice, and simply ran with it. It took just 11 days for them to close this case. And to this day, the mystery surrounding the SOS sign has been cast into the void of history, solved to them, yet completely bewildering to the world surrounding them.

By 1990, the bones were reexamined, and the consensus underwent a surprising change. Reportedly, they never belonged to a woman with Type O blood, but rather a man with Type A. (screen whooshes) (eerie music) (rain pattering) Why the hell were the bones suddenly reclassified?

Who was the man recorded on Kenji's tapes? How were these massive trees carried and placed by just one person? And how were these trees chopped down at all?

Taking a broader look at the landscape, we've established that the site of the SOS sign was reached by a diversion from the main Mount Asahi-dake trail. As we've seen, though, multiple hikers have done this. So how have they all made the exact same mistake?

So as it turns out, there is an incredibly confusing landmark on the mountain. It's a boulder called Safe Rock, and it's typically used by climbers to orient themselves on their trek, as once you encounter it, you're required to take a right turn to continue your journey to the peak. Bizarrely, however, there sits another identically shaped boulder right next to Safe Rock, called Fake Safe Rock.

Unlike the former, using this one as a guide diverts hikers to the much more dangerous south side of the mountain, terrain littered with steep cliffs and intense grades filled with a specific type of bamboo known locally as sasa. In recent years, Fake Safe Rock has been marked with a rope to signal that you shouldn't follow it. However, to this day, hikers often misinterpret it for the actual Safe Rock, adding even further confusion to an already disorienting situation.

I'm sure you're finding this convoluted as I'm explaining it to you. Now imagine if you were faced with this dilemma while exhausted in the wild and completely alone. (foreboding music) To this day, it's believed that both the Tokyo hikers and Kenji Iwamura made this mistake, leaving them both to be stranded and completely helpless.

So with this in mind, let's go forth and entertain the idea that Kenji Iwamura was the only one involved here. Let's just say that everything belongs to and was done by no one but him. So it went a little something (machine clicks) (machine whirring) like this.

(mysterious music) (machine continues whirring) Kenji Iwamura begins his trek from the lodge and makes his way up the Asahi-dake trail. Because of the impending storm, it's possible that there were few hikers up on the mountain. He makes his journey all the way up before the sky darkens and dense fog rolls in.

He encounters the Fake Safe Rock, confusing it for the real one, and makes a right turn, leading him south. As the day bleeds by, he begins to panic, the sky darkening as his psyche becomes ever more anxious. He recognizes not a single thing about the path he's on, and it becomes rapidly clear to him that he's venturing nowhere near the summit.

(mysterious music) (rain pattering) Completely turned around and with no other choice, he continues, following some semblance of a path, even though it's only heading down. Is he heading back to camp? Are there any towns in this direction?

Where exactly is he going? As hours pass, he becomes more panicked, and begins screaming for help, for anyone to hear him. He falls off a cliff on the way down and breaks two bones, and so, in immense distress, pulls out his Sony Walkman to record an SOS message, and later plays it on repeat to save himself from damaging his voice.

As he continues to limp downward, he encounters and crosses the Chubetsu River before eventually landing at his final destination, the flat wetland where he would build the SOS, and where the two would inevitably remain. (eerie music) (screen whooshes) (rain pattering) (wind whooshing) You know, on the surface, this theory makes sense. However, when you begin to pick apart the finer details, this story rapidly falls apart.

As we know, the only cliffs in the vicinity are up the mountain, and if these are what Kenji's referring to in his recording, assuming it's him, then he made it to the wetland with broken bones and in excruciating pain. Even if we give him the benefit of the doubt and say that he had every tool in the world, building a sign of this scale would take immense effort for just one person. It's been said that something like this would take two days to construct for someone healthy.

So how in the world did Kenji do this while critically injured? There was no ax ever found. And why would he have one on a mountain hike anyway?

On top of this, the condition of the bones indicated that he would've been incredibly frail by the time he passed away. There is no way this man made this thing alone, leading me to believe that Kenji Iwamura, perhaps, wasn't the only one to die there. Consider this.

(mysterious music) Kenji is on the hike, and somewhere during his climb, encounters someone else out there. The two are both on their way to the mountain peak, and so they pair up and continue their trek together. As the fog rolls in, the two begin to undergo equally critical errors, making their turn at Fake Safe Rock and getting lost down the mountain's south end.

Injured, one of them makes a recording while the other pleads to keep going. And so they continue downward, cross the river, and make it to the wetland where Kenji lies in agony. It's possible that this other hiker, for some, reason had an axe, and over the next few days, made this sign with incredibly limited help from Kenji.

Kenji knows he can't go any further, though. And so, in a final fit of desperation, (zipper buzzes) the other hiker grabs a handful of supplies and takes off to find them help. (mysterious music) In a way, this could explain why police never found an axe.

This could explain why the voice on the recording wasn't Kenji, and this potentially could explain how this sign was even made in the first place. The human body can go three days without water, and perhaps this unknown person used their last in a final push for rescue. At the end of it all, though, they would never make it, and instead would die a slow death, surrounded by darkness, by wilderness, and in a forest, completely abandoned.

(mysterious music) (rain pattering) (object scrapes and clacks) (rain pattering) Perhaps their body is still out there, but we just haven't found it yet. It's a tragic end to someone who may not even exist, but goddamn it, it's the only way this story makes any sense. Kenji Iwamura had to have gotten help from someone else on the mountain that night.

There is just no way in which he couldn't have. (rain pattering) (thunder rumbles) (foreboding music) I refuse to believe that there was just one person on Mount Asahi-dake that night. The circumstances are just too extraordinary for one to pull this off alone.

The broken bones, the stranger on the tape, the rapid closure, someone migrating literal tons of weight after vital injuries. Everything about this conflicts with the reality of the situation we've been given. These theories, as far-fetched as they are, are the only way this makes any sense in my brain.

And even then, I'm still assuming that someone had an axe, assuming that an entire second person was there, and assuming that this other person died and was never found elsewhere on the mountain. No matter which way we approach this, nothing makes sense without drawing vectors to things that may or may not have happened. And to me, that's what makes this incident so incredibly perplexing.

The man on the recording never stated that he was with someone. And even if we assume that Kenji wasn't alone, the only way this story makes any sort of sense, it's almost like the two of them never even knew the other existed. It's like two people encountered the exact same spot, just on completely different timelines.

(mysterious music) It goes without saying that we can theorize for hours about what took place on Mount Asahi-dake and how the SOS sign, given the evidence we currently have, shouldn't exist. But out of everything, the one detail that haunts me most about this is the simple fact that, at the end of everything, the police have never formally identified the bones as belonging to Kenji, and this is after they were reclassified to belonging to a male, after the story spread to the world around them, and after the mystery surrounding the SOS sign and all of its bizarre inconsistencies had spearheaded this into one of the most captivating unsolved cases in history. (suspenseful music) (rain pattering) There has never been an official answer as to who the bones belong to.

And to this day, nobody knows when the SOS sign was made and who in the world built it.