The Unsolved Mystery of a Japanese Man Found Dead in Dorm Room Septic Tank

The Youtube documentary "Unsolved Mystery: Japanese Man Found in Septic Tank" by Rhetorica is based on the following script. Make sure to watch the video for a more extensive coverage with video material and several (translated) news segments.

Introduction

On the 24^th of February 1989, the state funeral of Emperor Hirohito was held after his death on the 7^th of January. Hirohito had been the longest serving emperor in Japanese history from 1926 up until his death in 1989. Due to the state funeral of the emperor, workers across Japan were granted a day off from work. In the small mountain village of Miyakoji in Fukushima prefecture’s Tamura district, a 23-year old teacher (only known as A) took the opportunity to visit her family in another town for a couple of days. She left her dorm from the 24^th until the 27^th, after which she returned on the 28^th to continue her teaching at the local primary school. On the evening of the 28^th, A walked through the cold and snowy streets off Miyakoji, arriving at her dormitory overlooking the school playground. The teacher dorms at that time consisted of 4 small buildings, each a one-person dorm room with an attached bathroom. 

Dormitory buildings overlooking the playground

 

One of the dormitory buildings
at the time

During that time in rural Japan squatting toilets or “bottom toilets” were frequently used due to the older nature of buildings in remote villages. This particular dorm had a toilet with a septic tank placed right below the squatting pan, whereas the septic tank was U-shaped with one end linked to the squatting pan and another linked to the sewage outlet on the outside. Every so often the septic tank would be emptied manually from the outside.

Overview septic tank (numbers in centimeters): inlet from outside (left) and toilet (right)

Back of the dormitory building with inlet to the septic tank

The teacher in question entered the bathroom somewhere around 6pm, making use of the squatting toilet. However, right before she could use the toilet she casually peeked in and saw what appeared to be a shoe, upon further inspection she described seeing the possible outline of a human head. Startled and confused, the teacher decided to check the septic tank from the outside to see if it was just her mind playing tricks on her. Upon arrival outside, she noticed the lid of the septic tank was unlocked, which was unusual. Upon opening the lid, the teacher saw a pair of legs, after which she immediately ran to the vice principal and her co-workers who called the police.

 A police officer from the local police station followed by a member of the fire department rushed to the scene. Not long after, police officers from the Tamura police station got involved as well. Officers and firemen tried removing the person in question from the tank, though this seemed to be impossible due to the tank being too narrow to pull the person out. So much so, that only after digging out and destroying the septic tank with heavy machinery, the person in question could be removed from the tank. Soon after, it became clear that the person found in the septic tank had passed away, albeit in a very strange position. The person in question was identified as a male in his 20s, and was found lying on his back with his eyes pointing up into the squatting pan hole. On the left side of his slightly left-tilted face one of his shoes was found as seen earlier by the teacher. His knees were tucked upwards in order to fit into the tank. He was naked from the waste up and barefoot, but had a folded jacket pressed against his chest. After removing the body, police officers and fireman washed the body twice. The first time by a police officer on the spot using a hose, a second cleaning happened at the fire station. Only after washing the body twice, was the man handed over to the coroner for an autopsy.

Overview of position of the man

Autopsy results show only minor scratches on the man’s knees and elbows, without any signs of struggle. The cause of death was believed to be a combination of hypothermia as well as thoracic circulatory failure. According to the autopsy report, the man had likely entered the septic tank and froze to death. Further results state that the estimated time of death was 2 days prior to the discovery of his body, most likely on Sunday the 26^th based on the rigor mortis condition of the body.  

After their investigation the police concluded that the deceased man must’ve crawled into the septic tank to peek on women using the bathroom, they further believed no third party was involved. Even though many residents sternly disagreed with the police’s conclusions, the case was closed as an accidental death.

Victim

The deceased man was identified as 26-year old local resident Naoyuki Sugano. Among the community he was a well-known and generally respected man. While in high school Naoyuki was into sports and music, playing in a band and even writing his own songs. He earned his reputation around town by being particularly active in youth association activities, working as an MC at weddings and helping the sitting village mayor with his campaign. In the last years of Naoyuki’s life, he found himself working for a company supporting the nearby Daiichi power plant. A nuclear power plant only about a 30 minute drive from the village. Considered to be a reliable and very sociable man, many Miyakoji residents grew fond of him and considered him to have a bright future.

 

Naoyuki Sugano (26): victim found in septic tank

On the 23^rd, 5 days before his body was found, Naoyuki attended a farewell party for his senior though leaving the party early at 1 am. Naoyuki was last seen alive on the morning of Friday the 24^th by his father at around 10 am in the family residence where he lived with his parents and grandmother. Naoyuki’s father told police his son was not acting out of the ordinary and that he had left the property by car after saying he’d be running some errands and he’d be back soon (ちょっと行ってくるからな). His dad, watching TV, didn’t think anything of it. Just four days later though, Naoyuki’s body was found in the septic tank about a 10 minute drive from his home.

Overview of days around Naoyuki's death

Theories

Even though the case has been closed since 1989, many people believe there’s more to this incident than what is concluded by the police department. Let’s analyze the 3 most discussed theories as to what happened to Naoyuki and why.

The 3 most discussed theories

Theory #1: Naoyuki climbed in the septic tank himself

The police ruled out a 3^rd party in the matter and theorized that Naoyuki probably climbed in the septic himself, supposedly to peek on the female teacher. The villagers and especially Naoyuki’s father, however, didn’t feel anything for this theory. Naoyuki was a well-known and respected man, known to help others, his good reputation within Miyakoji even brought weight to his opinion in endorsing the sitting village mayor. A large part of Miyakoji’s residents were convinced Naoyuki didn’t just climb in the septic tank himself, and as a result within a month over 4000 villagers (more than half of the village’s population) decided to sign a request to the Tamura policed partment to re-investigate the matter. Sadly, to no avail.

Tamura police department

Multiple mysteries surround this case. And while climbing into the septic tank himself would seem plausible on the surface, a more detailed analysis may change your mind. Let’s look at some of the facts.

First of all, the weather was reported to be around 5 degrees Celsius, which is in concordance with February weather for the Fukushima area. In fact, it reportedly had been snowing 8 inches, making it hard to believe someone would climb in a septic tank barefoot and shirtless. Even more suspicious is where Naoyuki’s vehicle and other shoe were found. While one shoe was found next to his head in the septic tank, his other shoe was found on an embankment further up the street. Comparing this to the location of the septic tank, he’d have walked about 300 meters with at least one shoe missing. On top of that, Naoyuki’s car was found around a 100 meters from the toilet oddly parked unlocked and with the key still in the ignition, as if he’d planned only for a quick drop-off. If the police’s theory is correct, why would Naoyuki’s shoe and car be in completely different places and practically abandoned? This map shows an overview of satellite images comparing the different locations. 

 

Map showing the locations of  the shoe, car and dormitory

Location of Naoyuki's shoe

Location of Naoyuki's car

Probably the biggest mystery is though, how did Naoyuki get into the septic tank in the first place?

The following diagram has been made of the septic tank. On the right hand site the toilet inlet can be seen, which had an estimated diameter of 20 cm. On the left the entrance to the septic tank from the outside, and the most probable entrance for Naoyuki’s body, can be found with a diameter of around 36 cm. Naoyuki’s length was estimated to be 170 cm, which according to the Ministry of Economy, trade and industry’s 2004-2006 survey fits with an average shoulder width for men aged 25-29 years old as 40.4 cm. Even so, if you’d take the physical appearance of a smaller woman, he’d barely be able to fit the manhole of 36 cm diameter either.

 

Diagram with analysis of the septic tank

Naoyuki’s father appeared on a Fuji TV program 5 years after the incident, still determined to show the world something more sinister happened to his son. He brings a book full of pictures surrounding the case and even managed to get the same septic tank back to its original state as evidence for his case. On the program, the original dorm rooms are shown, which later got removed and replaced by the one building unit that’s still there to this day as shown on these 2016 pictures. Naoyuki’s father goes on to show the original U-shaped construction to the news crew, after which one of the members resembling Naoyuki’s physical characteristics tries to climb into the outside entrance. Needless to say, he ends up not getting very far after the other members of the news crew have to pull him out, proving the point Naoyuki’s father is trying to make. 

 

Naoyuki's father

Dormitory was demolished and replaced with the building in this picture

Screenshot of a crew member trying to climb in the original septic tank
Watch the video in the Rhetorica documentary.

Another interesting statement by the police and specifically the coroner was the time of death. According to the autopsy report Naoyuki’s death was estimated to be Sunday the 26^th of February. Now, even though this estimate is based on rigor mortis, or the stiffness of muscles, a lot of factors have to be taken into account to make a good estimate of the time of death according to forensic scientists. Unfortunately, conditions were pretty unique, being Naoyuki was found in a septic tank in extremely cold temperatures. While the estimate can be questioned, let’s say the coroner was right. What happened to Naoyuki between the morning of the 24^th and his estimated death on the 26^th? It was later revealed that Naoyuki was acquainted with the teacher and probably could’ve known she planned to leave her dorm till at least the 27^th to visit her hometown. Even if he would want to peek, this would probably be the worst possible timing he could’ve chosen.

Article about the incident with original septic tank

The police’s theory is, however, not just based on thin air. Before and after the incident, there have been multiple similar cases of Japanese men climbing in sewage drains to peek at unsuspecting women. Take for example the case of 28 year old Yasuomi Hirai in 2015. He managed to climb into a 60 cm deep and 28 cm wide sewer pipe to take pictures of women underwear. In contrast to Naoyuki, however, he’d been arrested before for similar reasons and was known to wander around women’s toilets in the years before his arrest in 2015. Even confessing to police “I want to reincarnate as a street surface so I can look comfortable at women’s underwear”. Naoyuki was, however, known as a stand-up guy that would never do such a thing. He was in fact so well respected that more than half of his hometown petitioned the police to re-investigate the case.

Sketch about Yasuomi Hirai

Another angle some have discussed is that somehow the police tried covering up Naoyuki’s murder. Villagers grew more and more suspicious of the local police chief due to the police’s subpar handling of the case, especially after refusing to re-investigate the matter. Fuji TV reporters managed to get an interview at the police station 5 years after Naoyuki’s death, though more or less the same statements were made as what is in the final police report. It was said that when the body was found, the crime scene was visited by multiple officers and Miyakoji residents. There was reportedly no crime scene tape and no pictures of the crime scene were taken by police, making it nearly impossible to investigate evidence as footprints and fingerprints. On top of that, the body had been hosed down at the crime scene and again at the fire station before the autopsy took place. Evidence of a struggle, such as debris under Naoyuki’s nails, could have been washed away by this process. Even more mysterious are the rumors that both the officer who cleaned Naoyuki at the crime scene and the coroner who performed the autopsy retired immediately after the case.

While no hard evidence shows the police’s theory can be debunked, you can’t help but notice there are very strange aspects to this case. 

Theory #2: Murdered in relation to the teacher and her fiancée

Naoyuki and the teacher who found his body happen to know each other. In fact, Naoyuki was reportedly good friends with the teacher’s fiancée, which caused him to be acquainted with the teacher as well. Other than that, Naoyuki helped the teacher with organizing a sports event at the school where she worked through one of his youth association activities. Even more interesting for this particular case is that the teacher was stalked or pranked by telephone. Naoyuki took it upon himself to help by recording the calls and trying to figure out who the culprit was. At one point Naoyuki brought the recordings to the police, but the police had no interest in the case. Seemingly frustrated, Naoyuki tried pursuing the case by himself. A friend of his mentioned that Naoyuki at one point almost figured out who made the telephone calls, which could’ve been another interesting lead in this case.

Some speculate that the teacher possibly couldn’t have seen the shoe in a dimly lit septic tank, especially not while casually looking in. On top of that, the teacher went to check in the septic tank from the outside by herself first, and only after finding signs of a body did she notify other staff members. By touching the lid and telling others she did so, fingerprint evidence wouldn’t be as reliable anymore. This might’ve been a way she covered her tracks in connection to the crime scene, though admittedly it would’ve been less likely considering the other circumstances.

Another rumor related to the teacher consist of her and Naoyuki having an affair, making the teacher’s fiancée a person of interest as well. All that is known is that the three knew each other at least fairly well and that no concrete evidence points towards either the teacher or her fiancée.

Theory #3: Murdered in relation to the local election

10 days prior to the estimated time of death, an election took place for village mayor. The mayoral election was particularly tough in 1989 as the decision whether or not to support nuclear energy provided by the Daiichi power plant just 26 km away divided the village. On one hand, villagers understood that nuclear energy would create jobs for the region, Naoyuki as an employee of a company supporting the power plant promoted this narrative. Others had major concerns about the harm it could do to their surroundings, and in their defense, they were not wrong. Previous to the election multiple incidents happened at the nearby Fukushima Daiichi nuclear power plant. In fact, a month before the election (in January) a welded joint in a circulating pomp caused reactor 3 to shut down temporarily. Allegedly, a large leak followed after the incident. The team at the reactor was at great stress and one of the employees committed suicide at Tokyo’s Ueno station shortly after the incident. Little did anyone know that Fukushima’s Daiichi nuclear power plant, just a 30 minute drive away from Miyakoji village, would cause immense destruction 22 years later after a tsunami caused damage to the power plant and contaminated a large part of the surroundings. Miyakoji was among several villages in the 30 km evacuation zone after the earthquake and following tsunami destroyed the power plant.

 

Miyakoji just 26 km from the now damaged nuclear power plant in Fukushima

Nevertheless, Naoyuki’s endorsements to the pro-nuclear energy mayor suddenly discontinued shortly before the election. Naoyuki worked for a company supporting the power plant and had on his own time endorsed the sitting mayor by writing several speeches. Naoyuki had supposedly told a friend on the 24^th, the last day he was seen alive, “I have to meet someone tomorrow” not going into further detail. These Circumstances are definitely suspicious. 

It was later reported that management of the power plant had bribed the sitting mayor for around 800 million yen, due to the influence the mayor had over whether or not the power plant could resume its activities in the area. According to some, Naoyuki was also seen leaving during a speech of the sitting mayor around the time his support discontinued. Some speculate that Naoyuki found out about the bribe and didn’t want anything to do with it. This might have caused some of the people involved in the bribe to be concerned and ending up murdering Naoyuki. Others have said that the body was placed deliberately in a place in which it would be found relatively easy, so that it would function as a message for others who might have known about the bribe. While no hard evidence of any involvement of the mayor election and the power plant has ever surfaced, circumstances are definitely suspicious.

Conclusion

This strange case still manages to raise eyebrows all these years later, leaving a lasting impact on the quiet mountain village of Miyakoji. Even more, a movie called Barizogon (バリゾーゴン) (translated meaning “profanity”produced by Fumiki Watanabe was made in 1996 loosely based on Naoyuki’s death.

Movie poster of Barizogon

Even with multiple unexplainable rumors surrounding this case, the mysterious death of Naoyuki Sugano was never properly reinvestigated. Since then, due to the statute of limitations in Japan the case was closed, and we’re left wondering what actually happened with Naoyuki Sugano. 

My thoughts go out to the Sugano family and Naoyuki's friends, may Naoyuki rest in peace.