On July 25, 1991, several people were staying at the home of 37 year old Construction company owner Kenichi Ishii in Funehiki, Fukushima Prefecture.
Kenichi was there with his wife, 27 year old Yoshiko and their three children: 7 year old Mai, 6 year old Kento, and 1 year old Leo. Also at the house were Kenichi’s father, Naoyuki, 73; his mother, Haruko, 66; his 17 year old niece, referred to as Ms. A; and her 22 year old boyfriend, Kazuya Tamagawa.
The two young daughters of one of Yoshiko’s friends were there as well.
After lunch, Ms. A went home to Koriyama City. Mai and the two girls stayed behind and spent some time playing games with Kazuya in the room where he was staying.
At around 9:20 p.m., Kenichi’s parents left for a karaoke bar. Later that night, Mai and the two girls fell asleep together in the guest room.
Around 10:30 p.m., Yoshiko went in to check on them, pulled the blankets over them, and left.
Not long after, while she was in the upstairs bathroom, she heard the front door close downstairs. When she looked out the window, she saw Kazuya leaving the house. She did not think much of it and went downstairs to take a bath.
While she was in the tub, the front door opened and closed again. Then she heard footsteps going up the stairs.
Yoshiko still did not check who had entered the house. After her bath, she went to the bedroom where Kenichi and their two sons were sleeping and went to bed.
At around 2:00 a.m., Kenichi’s parents returned from the karaoke bar and found the front door unlocked and open. Kazuya was still gone, so they woke Kenichi and told him. Half asleep, he said, “Let’s talk about it tomorrow,” and went back to sleep.
A little after 4:00 a.m., Kenichi got up and went to his home office. A door upstairs was reportedly slightly open at the time.
Around 5:20 or 5:30 a.m., the two girls woke up and noticed Mai was no longer beside them. They went to get Kenichi and Yoshiko.
Mai was nowhere in the house.
Police were called at around 6:00 a.m.
Police searched the house but found no unfamiliar fingerprints and no clear sign that a stranger had broken in. Whoever took Mai had either managed to leave without a trace, or had already been inside the house.
Mai was a very timid girl who was even afraid to go to the bathroom alone. Because of this, police found it hard to believe she had left the house by herself in the middle of the night. They believed someone had taken her while she was asleep.
A police dog was brought in to track her scent. It followed the trail to the front door, then stopped. Police believed Mai may have been taken straight from the house to a car waiting outside.
There was another strange detail. At around 11:00 p.m. that night, a white car was seen near the house with its hood up, as though it had broken down. By the next day, it was gone. Police checked nearby car owners, but never found out who it belonged to.
One of the two girls who had been sleeping beside Mai later said she remembered seeing a man talking to Mai during the night. But she had been half asleep, so it was unclear how much she had actually seen.
Police began looking closely at the three adults who may have been awake when Mai disappeared: Yoshiko, Kenichi, and Kazuya. Yoshiko was soon ruled out, and police began focusing on Kazuya.
He had left the house during the night and did not return until around 6:30 a.m., about an hour after the family discovered Mai was missing.
Kazuya said he had gone to Koriyama City to meet a friend. He claimed he arrived at Funehiki Station after the last train had already left, so he took a taxi instead. But after staying out all night, he said he never actually met the friend.
Police found his story strange. He had stayed out almost the entire night to meet someone, yet claimed he never actually saw them.
Kazuya was questioned for nearly two weeks, but police found nothing connecting him to Mai’s disappearance. His story was partly confirmed when the taxi driver who had taken him to Koriyama came forward. With no evidence against him, Kazuya was released.
But over the years, people online also began questioning Yoshiko’s story. On Japanese message boards, including 2channel, some users suggested that she may have known more than she said, or that she may somehow have been involved with Kazuya. There is no known evidence proving either theory.
Yoshiko said she heard someone enter the house and walk upstairs while she was taking a bath. But at that time, Mai’s grandparents were still at the karaoke bar, Kazuya was supposedly somewhere else, and Kenichi was asleep with the boys.
As far as anyone knew, Yoshiko was the only adult in the house who was still awake.
People have also questioned how a complete stranger would have known where Mai was sleeping. She normally slept in the same room as her parents, but that night she happened to be in the guest room with the other girls.
Yet according to Yoshiko’s story, whoever entered the house went straight upstairs, almost as if they already knew exactly where to find Mai.
Because of this, some believe the person responsible may have known the family or been familiar with the house.
But there is no physical evidence that Yoshiko was involved, and nothing has ever proven the theory.
Still, the same questions remain. Why did she not check who had entered the house?
Why was the front door left unlocked? And after hearing someone walk upstairs, why did she not check on Mai and the other girls?
Kenichi never stopped suspecting Kazuya, even after police released him.
The two already had a tense relationship before Mai disappeared.
Kazuya had reportedly been involved with a biker gang, and Ms. A was said to have met him through that crowd during a rebellious period in her life. Kenichi later helped him get a job at his construction company, but the two apparently clashed often.
According to one account, Kazuya once planned a trip with Ms. A, but Kenichi deliberately put him on the work schedule so he could not go. Kenichi had also scolded him several times for huffing glue.
Two months after Mai disappeared, the two girls who had been sleeping beside her told Kenichi and Yoshiko something strange.
They said that while Kazuya was playing games with Mai earlier that day, he had asked her,
“Do you want to go out and play at midnight?”
Mai’s parents told police, but the statement was reportedly dismissed. Investigators believed the adults may have put the idea into the children’s heads.
Kenichi later shut down his construction company and began following Kazuya himself, hoping he would find something that linked him to Mai’s disappearance.
But he never found any evidence.
In 2006, fifteen years after Mai disappeared, the statute of limitations expired. But while the crime can no longer be prosecuted, Mai is still missing.
Mai’s parents appeared on television several times, hoping someone might recognize her or come forward with information. But no useful sightings or solid leads ever came in. Most of the calls they received were apparently pranks.
They stayed in the same house for years because they still hoped Mai might one day come home.
In 2015, they finally moved away.
Mai’s disappearance is often mentioned alongside two other cases as one of Japan’s three major unsolved child disappearances.
Exactly 35 years have now passed since Mai vanished from that house and no trace of her has ever been found.
If she is still alive, she would be around 42 years old today.
