[Mito Nail Technician Murder] Suspect Placed Tracker in Plush Toy, Obsessively Stalked Victim

A tragedy on New Year’s Eve evening

On January 22, more than 20 media outlets, including newspapers and television stations, gathered at the Mito Police Station of the Ibaraki Prefectural Police from early morning. Takumi Ōuchi (28) appeared at the station’s secured transfer entrance, surrounded by chain-link fencing, shortly after 9 a.m. His hair was neatly arranged, giving a tidy impression. He did not hide his face from the cameras, and walked to the transfer vehicle with a slightly sulky gait, shoulders moving as he went.

Ōuchi was arrested the previous day, January 21, on suspicion of murdering Haruka Komatsumoto (31), a nail technician living in an apartment in Mito City at the end of last year.

“The incident came to light around 7:15 p.m. on New Year’s Eve last year. Her husband (27) returned home to find Ms. Komatsumoto lying at the entrance, covered in blood. That morning, the two had gone shopping together, after which her husband went to work. Around 5 p.m., Ms. Komatsumoto called her husband saying she was on her way home. The crime is believed to have occurred between 5:20 p.m. and 7:15 p.m.” (Reporter, national newspaper social affairs desk)

Ms. Komatsumoto had multiple blunt-force injuries to her head, and a stab wound to the right side of her neck that reached an artery. She was reportedly pregnant and may have instinctively tried to protect her abdomen. Her arms bore more than a dozen cuts and bruises, likely from resisting. Blood had splattered onto the walls, indicating that the perpetrator attacked the resisting Ms. Komatsumoto with multiple weapons and with strong intent to kill. The cause of death was traumatic shock from the head injuries and neck stabbing.

It was also revealed that four days before the incident, Ms. Komatsumoto had called the police asking, “If I want to consult about something like stalking from an ex-boyfriend, where should I go?” She asked whether it could be handled even at night. When the police said yes and asked for her name and contact information, she replied, “I will come later,” and ended the call.

When the police analyzed Ms. Komatsumoto’s smartphone, her former boyfriend, Ōuchi, was identified. He is believed to be the ex-boyfriend she referred to. What was the relationship between the two?

“Ms. Komatsumoto had previously worked at a cabaret club in Mito, where she apparently met him. They began dating in 2024 but broke up within the same year. Around the summer of 2025, he began sending messages via social media pressuring her to reconcile and expressing resentment. Ms. Komatsumoto blocked him and cut off contact. After that, Ōuchi reportedly asked her acquaintances to find out where she was living.” (Same source)

How did Ōuchi manage to identify Ms. Komatsumoto’s address? The police investigation revealed a shocking method.

Love amplified in a distorted way

“When the police examined the stuffed toy in Ms. Komatsumoto’s room, they found it contained a loss-prevention tag that sent location information to the suspect’s smartphone. That popular character plush had been delivered a few days before the incident to Ms. Komatsumoto’s family home, labeled as a prize for contest winners from a theme park operator, and was later kept at her apartment.”

Why was Ōuchi so obsessed with Ms. Komatsumoto? Regarding the case, crime journalist Taihei Ogawa speculates, “His feelings must have been that strong.”

“Even he probably knew rationally that it was impossible. Yet he couldn’t give up hope, thinking, ‘Maybe there’s still a chance,’ and took action. But he was blocked by the woman and couldn’t contact her. The woman he had dated two years earlier had now built a separate life and was happy. As these facts accumulated in his mind, his affection amplified in a distorted way and increasingly trapped him.

Ideally, the victim should have consulted the police with her real name and taken measures. I don’t know why she asked anonymously, but there was probably some psychological reason for not wanting to reveal her identity.

The police have a duty of confidentiality, and if approached properly, they will respond. However, given cases like the one in Kawasaki, there is a fact that they are not fully trusted. That’s why, when the police receive a consultation, they need to sincerely engage from the victim’s standpoint.”

Ōuchi reportedly denied the allegations in questioning, saying, “I have nothing to do with this and know nothing.” On the other hand, a car believed to belong to him was captured by security cameras around the apartment before and after the incident.

Though reportedly liked by his friends, Ōuchi has now taken away both Ms. Komatsumoto’s happiness and her future. One wonders what feelings he harbors toward her now.