Unsolved mysteries in Japan

Japan has many urban legends that will send chills down your spine. However, legends ultimately have an element of fiction. If you’re looking for some real stories, we’ve compiled a list of unsolved mysteries in Japan that have baffled the nation for ages. 

Most of these mysteries are pretty unsettling, so we don’t recommend this article for bedtime reading if you still want to sleep tonight.

1. A dead body stuck in the septic tank

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Image credit:
Possessed Photography

Japan’s sewage system of old is nowhere near the technologically-advanced toilets you see today. Back then, it merely comprised a septic tank which stored human excretion for later transportation.

unsolved mysteries in Japan - miyakoji district
Modern-day Miyakoji District
Image credit: Wikimedia Commons

However, on 28th February 1989, a female teacher in Miyakoji Village, Fukushima, found more than just human waste in her single-room dormitory’s U-shaped septic tank. In fact, she found a human body.

unsolved mysteries in Japan - septic tank diagram
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Unsolved Mysteries

The body belonged to a topless man. He was found in a fetal position hugging his own clothes, with his face facing the toilet hole. A shoe was placed beside his head, while his other shoe was found at a faraway river bank.

Because of how small the openings of the septic tank were, the police had difficulty retrieving the body, to the point where they had to cut the septic tank in order to do so.

The victim was later identified as the 26-year-old Naoyuki Kanno. He was reported missing on 24th February, four days before the discovery of his body. Reports revealed that he died on 26th February.

In the end, the case was dismissed as a case of peeping. Police believed that Naoyuki entered the septic tank to look at women relieving themselves, only to accidentally die of hypothermia. However, many villagers found the verdict unacceptable as the victim, who participated actively in many village events, was known to be an amiable person. 

Moreover, given his position in the tank, it is likely that the man entered head-first – there was no way he could have turned around within the cramped 125cm x 47cm tank. Logically, this is an unnatural way for someone to enter a septic tank voluntarily. The other piece of evidence pointing towards foul play was his shoe, which was found far away from the crime scene.

2. The Paraquat Murders

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Darren Halstead

Also known as the Vending Machine Murders, the Paraquat Murders was a series of drink poisoning incidents that occured in the 1980s and 1990s.

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Wikimedia Commons

In 1985, Oronamin C, a vitamin drink brand popular amongst the elders, was holding a free drink promotion. When  you bought a drink from a vending machine, a bottle of Oronamin C would be dispensed along with your purchase.

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Four Seasons

Sadly, this harmless promotion became deadly when someone placed a bottle of Oronamin C poisoned with paraquat – a highly toxic weed killer – in the collection port of a vending machine. 

On 30th April 1985, a person saw the lone drink and took it, assuming that it was leftover from another customer who didn’t want the extra drink. They died after consuming the poisoned drink.

11 more murders then followed, ten of which involved paraquat poisoning. One involved diquat, an equally deadly herbicide.

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Wikimedia Commons

The police were unable to get more leads because the vending machines involved in the cases were all located in secluded areas without much human traffic or surveillance. However, the police surmised that the perpetrator must work in an industrial area. This is because paraquat could not be obtained easily elsewhere.

3. The Coca-Cola murders

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Image credit:
Jan Böttinger

8 years before the Vending Machine murders took place, a similar incident involving poisoned drinks troubled Tokyo and Osaka. This case, which took place in 1977, involved cyanide-laced Coca-Cola, and was thus dubbed the Coca-Cola murders.

unsolved mysteries in Japan - JR shinagawa
Modern-day Shinagawa Station
Image credit: Wikimedia Commons

On 3rd January 1977, a high school student found an unattended bottle of Coca-Cola at a public payphone near Shinagawa Station. He consumed the poisoned drink at 1AM and was rushed to the hospital. He eventually succumbed to cyanide poisoning.

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News report on the youth’s death.
Image credit: @caw534021

On that same morning, a 46-year-old worker consumed a similarly poisoned drink and eventually passed away too. His body was found 600m away from where the student found the first bottle of Coca-Cola.

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The police quickly sprang into action and put up many notices warning the public not to consume unattended bottles of Coca-Cola lying around. Owing to the notices and some luck, a 15-year-old boy narrowly escaped death. 

He actually found a bottle of Coca-Cola at the public telephone located near his family’s store one day, and was intending to drink it later on. However, he then caught wind of the police notices, realised that something was wrong, and reported the bottle instead.

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Unfortunately, a third case of cyanide poisoning still happened in Osaka despite public warnings. A 39-year-old man found a bottle of Coca-Cola at the payphone and drank it. The medical staff managed to save his life, but he committed suicide a day later out of shame.

The perpetrator was never caught in the end, and this incident forced Coca-Cola to change their product sealing to make it harder to tamper with.

4. The case of the SOS sign in Daisetsuzan National Park

unsolved mysteries in Japan - mount asahidake
Mount Asahidake
Image credit: Eco190

As Hokkaido’s largest national park, Daisetsuzan National Park is blessed with beautiful mountains, one of which is Mount Asahidake. However, it is also the home to one of Japan’s most chilling unsolved mysteries involving a giant SOS sign, a tape recording, and a skeleton.

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ノストラダムスの大事件・事故 AccidentsIncidents Nostradamus

On 24th July 1989, a helicopter dispatched to find 2 missing hikers came across a giant SOS sign measuring 4.8m x 3m. It was made using birch wood and was located 4km away from the peak of Mount Asahidake.

The rescuers ended up finding the 2 missing hikers, but the duo told the rescuers that they didn’t make the SOS sign.

A 2nd search was conducted. This time, a skeleton with broken bones and a bag pack were found 10-30m away from the SOS sign. In the bag, there was a tape recorder. You can hear the recording here.

unsolved mysteries in Japan - released tape
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ノストラダムスの大事件・事故 AccidentsIncidents Nostradamus

In the recording, a man can be heard dragging out the following words: “SOS, 助けてくれ。崖の上で身動きとれず。ここから吊り上げてくれ。” It translates to, “SOS, help me. I am on the cliff, I can’t move. Please lift me up from here.”

The bag also held a hiker ID belonging to a man named Kenji Iwamura. He went missing about 5 years ago in July 1984, according to a report in the Asahi Shimbun on 1st March 1991. DNA analysis eventually determined that the skeleton belonged to a male with type A blood, thereby solidifying the fact that the skeleton belonged to the missing hiker, who also had type A blood.

However, the circumstances that led to his eventual death remain a mystery.

5. The massacre of the Miyazawa family in Setagaya

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Seijo Police Special Investigation Headquarters

The Miyazawa family was a family of four, consisting of 44-year-old father Mikio Miyazawa, 41-year-old mother Yasuko Miyazawa, and their two kids, Niina Miyazawa and Rei Miyazawa.

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The victims’ residence.
Image credit: Thirteen-fri

On 30th December 2000, a man climbed a tree outside of the Miyazaki residence and entered the second floor. He strangled the six-year-old Rei to death, and subsequently murdered his father Mikio with a sashimi knife. The mother and daughter were subsequently killed with the same knife.

unsolved mysteries in Japan - murder weapon
Image adapted from:
Seijo Police Special Investigation Headquarters

The killer then stayed in the Miyazawa residence for around two to ten hours. He used the family computer, consumed food and drinks from their refrigerator, and even treated his wounds. He only left when Yasuko’s mother arrived.

unsolved mysteries in Japan - murderer's appearance
Image adapted from:
Seijo Police Special Investigation Headquarters

The killer left many traces of DNA, which helped police deduce that he’s a male about 170cm tall. He’s likely of a mixed descent from Asia and Europe, with a one in four chance of being Korean. 

However, till today, the killer roams the streets scot-free. The police are offering a reward of up to 20 million yen for any new leads. A detailed list of case findings can be found here.

6. The murder of a mother and her children in Aichi Prefecture

unsolved mysteries in Japan - aichi prefecture
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Aichi Police

On 9th September 2004, a concerned neighbour dialed 119 as a house nearby was on fire. In the house, there were four bodies. They belonged to a mother named Kato Toshiyo, and her three children, Kato Yuuki, Kato Rina, and Kato Shougo. That day was also Shougo’s birthday – his ambition was to become a policeman in the future.

Upon seeing streaks of kerosene and unusual damage dealt to the bodies, police suspected foul play and called for an investigation. Autopsy of the bodies revealed that the female bodies were marked with stab wounds, while the male bodies suffered heavy blows to the head.

Investigations revealed that when Toshiyo’s husband called at 11PM, everything was still fine. Police also found that the culprit likely brought kerosene, since there was none kept in the household.

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Sadly, the fire erased any other clues the police could follow up on. The case has remained cold for 17 years and counting. The Aichi Police continue to await any new leads.

7. The missing girl who went bamboo shoot picking

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Image credit:
Wikimedia Commons

On 29th April 2005, there was a bamboo shoot picking event held at a park in Kagawa Prefecture. Five-year-old Yuki Onishi participated in the event with her family. At some point in time, she decided to go elsewhere to pick up more bamboo shoots. Tragically, she never returned.

The police and a volunteer search party conducted searches that day and the day after, but to no avail. The strangest part about the case is that all of the five trained police dogs lost the girl’s scent at the exact same spot.

unsolved mysteries in Japan - missing girl
Image adapted from:
Tara A. Devlin

Yuki Onishi was 105cm tall and wore a pink hat, striped long-sleeved shirt, and pink shoes at the time of her disappearance.

8. The teenage girls who disappeared for 25 years

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On 5th May 1996, at 9PM, 19-year-old Narumi Takumi and Megumi Yashiki informed their families that they were going to Uozu City. Allegedly, they intended to check out a deserted hotel called “Hotel Tsubono”.

The duo drove off in Yashiki’s car, but never came back.

The case went cold until a witness came forward in end-2014 and revealed that they saw a car reverse into the sea at Kaihomaru Park at midnight, during a major holiday in 1996. This coincided with the timing of the girls’ disappearance.

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Following the prompt, a team of 35 rescuers fished out a vehicle on the seabed of Fushiki Port on 4th March 2020. The girls who disappeared for 25 years were finally found.

However, the reason why the car ended up in the sea remains an unsolved mystery. Many believe that the girls might have stepped on the accelerator when the car was in reverse, causing the car to accelerate backwards.

9. The girl who went missing from Yamanashi campsite

unsolved mysteries in Japan - yamanashi missing girl
Poster calling for help for the missing girl
Image credit: @mofuzebotto

Compared to the others on this list, this unsolved case is a relatively new case.

On 21st September 2019, seven families were camping at the Tsubakiso Campground in Doshi Village, Yamanashi Prefecture. Amongst the 27 campers was a seven-year-old girl named Misaki Ogura, who vanished into thin air sometime between 3.40PM-4PM that day.

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plus 9

She was last seen playing with a group of children, but when the group returned, she wasn’t with them. She was wearing a black, long-sleeved shirt and jeans.

Intensive searches went on for a few days. On 24th September 2019, about 60 people and a rescue dog were mobilised.

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Unfortunately, the search continues till today. Posters requesting for any clues have been placed around the vicinity of the campsite and also shared online.

10. Yonaguni Monument – the underwater city in Japan

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Image credit:
Wikimedia Commons

In 1987, a diver discovered a strange structure underwater while diving off the coast of Yonaguni Island.

The origin of the elaborate structure was hotly debated between two camps – those who believe it’s manmade, and those who believe it’s shaped by natural phenomena.

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Possible stairway of the main terrace
Image credit: Wikimedia Commons

The geologists who believe that the formation is natural point out that the structure is made of sandstone. The sandstone has lines of weaknesses where the rock is more vulnerable to fracturing. Since the monument is situated in an earthquake-prone region, it’s likely that the sandstone has fractured along those lines due to tectonic activities, resulting in the structure.

Meanwhile, those who advocate for the manmade theory point out how the monument looks like different parts of a city. They believe that the monument used to be an on-land civilization before it was submerged due to rising sea levels.

11. Do not trust what Yoko says

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On 2nd September 1994, 27-year-old housewife Mayumi Arashi claimed to be meeting a female friend she had known during her schooling years. However, said friend clarified the following day that Mayumi never did meet up with her. Yet, Mayumi did not return home, leaving behind her newborn son.

The case had no progress for many years, until a 2011 interview carried out by Super J Channel, a show run by Asahi TV, revealed an eerie tension that ran in the Arashi family.

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In the background of Mayumi’s father’s interview, a piece of paper can be seen taped to the bookshelf behind him. The note says, “洋子のはなしは信じるな”, which roughly translates to “Don’t trust what Yoko says.”

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Yoko is the younger sister of Mayumi. Before the father was interviewed, Yoko recounted the circumstances surrounding Mayumi. She claimed that on 2nd September 1994, Mayumi informed her that she would be meeting up with a certain classmate. But the classmate denied that such plans had been made.

Instead, Yoko then found a note in her wardrobe, supposedly left behind by Mayumi. The note said that she was going to meet up with another classmate, but was “betrayed”. There was a phone number written on the note – it belonged to said classmate. Yoko then called the number, and the classmate confirmed that Mayumi had indeed met up with them.

Yoko then claimed that she engaged a private detective to check on the classmate. A lead seemed to surface on 9th March 1995, when the classmate was seen entering the woods with two drinks, but a subsequent search conducted yielded no progress.

Allegedly, Yoko then went missing later on. In 2015, some netizens realised that Mayumi’s contact information on the Missing Person Search Support Association of Japan had been erased. Taking its place was a simple message saying,  “Thank you for everyone’s cooperation.” Currently, Mayumi’s information can no longer be found on the website.

Till today, we do not know what had happened to the sisters, and what the ominous note means.

12. The Glico-Morinaga Incident

Officially regarded as Metropolitan Designated Case 114, this is one of Japan’s most baffling cases to date.

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Image credit:
Wikimedia Commons

A mysterious person or organisation named “The Monster With 21 Faces” targeted food manufacturing companies, notably Glico and Morinaga, by harassing their employees and lacing their products with poison. Glico is the maker of Pocky, while Morinaga makes confectionery such as Hi-Chew.

The incident began with the kidnapping of the head of Glico, Katsuhisa Glico, on 18th March 1984. His home was broken into and he was kidnapped. A ransom of 1 billion yen was demanded, but the victim managed to escape two days later, stating that he wasn’t being watched. Thereafter, some of Glico’s employees had their cars set on fire.

A letter was then sent to the company, stating that their products had been laced with poison. This forced Glico to retract its products, causing a massive loss of more than ¥20 million. However, no poisoned products were found in the end.

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Illustration of The Fiend with Twenty Faces
Image credit: Amazon

In the letter, the culprit called themselves “The Monster With 21 Faces”, referencing Japanese mystery writer Edogawa Ranpo’s fictional villain “The Fiend with Twenty Faces”. After the first letter, they subsequently sent letters to the media, chiding the police force for their incompetence. 

To mock the police, they even gave hints, such as the colour of the vehicle they were using and how they managed to enter Glico’s premises.

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Wikimedia Commons

After the warning that Glico’s products were poisoned was released, a security camera caught footage of a man in a Yomiuri Giants baseball cap placing Glico’s chocolate on a store shelf. However, the footage yielded no subsequent leads.

On 26th June 1984, the perpetrator(s) made an announcement that Glico was forgiven, and that they would no longer target the company.

Instead, the spotlight was shifted to Marudai, a company that sells ham and sausages. They agreed to stop if the company paid them ¥584,000 (~USD5,369.72) and Marudai complied. On 28th June 1984, an undercover police officer disguised as an employee went on the mission to deliver the money. 

He was made to board a train from Osaka to Kyoto and was told to look out for a man with a white flag. However, said white flag never showed up even after the undercover agent reached Kyoto. However, he did notice a man with “fox eyes” following him throughout. 

The policeman boarded a train back to Osaka, but decided to alight midway in an attempt to tail the man instead. Unfortunately, the secretive man managed to slip away.

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Image credit:
Wikimedia Commons

After this incident, The Monster With 21 Faces turned their attention to confectionery company Morinaga. They stated that they had placed poison in Morinaga’s products, causing a massive recall that led to great financial losses. But unlike Glico’s case, actual poison was found on 21 of Morinaga’s products, along with tags that read “Made with toxins”.

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House Food Corporation, most famous for their curry products, was the next target. They were made to pay 1 million yen, lest their products get poisoned. The company agreed and sent a vehicle to transport the money to them. The police were tailing the vehicle.

However, the appointment was then cancelled promptly when the vehicle reached the rendezvous spot. As it turned out, an hour before the meeting, a stolen vehicle was spotted near the meeting area. A man estimated to be in his 40s had access to all the radio transmissions between the police. He managed to escape.

The whole fiasco, which was later known as the Glico-Morinaga Incident, only ceased when Yamamoto, the police superintendent who led the search for the Monster With 21 Faces, committed suicide by setting himself on fire. 

The Monster With 21 Faces left a final message saying how they would stop out of respect for Yamamoto’s passing, and that if there were any further extortions, they were people trying to copy them. The final message also included a chilling quote, which translates to “It’s fun to lead a bad man’s life.”

Unsolved mysteries in Japan that will unnerve you

These tales may sound like fictitious stories you’d hear at a spooky storytelling session, but keep in mind that they are very real events that have occurred. We can only hope that time will heal those who are affected, and reveal the truth in the future.

For more articles, check out:

Cover image adapted from (clockwise from top left): Thirteen-fri, Wikimedia Commons, h i k o, and Wikimedia Commons

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