A 29-year-old man was sentenced to 20 years in prison on Wednesday for the murder of his ex-girlfriend in Mito, Ibaraki Prefecture. The Mito District Court ruled against Takumi Ouchi, who prosecutors charged with killing 31-year-old nail artist Haruka Komatsumoto on December 31, 2025.

According to the indictment, Ouchi struck Komatsumoto multiple times on the head with a hammer and stabbed her neck with a knife inside her apartment. The court documents also state that Ouchi had been loitering near her residence for several days prior to the attack and secretly planted a tracking device on her car.

Prosecutors said Komatsumoto ended her relationship with Ouchi in November 2024, but he was unable to accept the breakup. After she blocked his phone number, prosecutors claimed Ouchi began to contemplate murder as a way to "reset" his life to a time before they met. They described the crime as premeditated, noting that Ouchi had purchased the hammer in advance and inflicted injuries on at least 48 parts of Komatsumoto's body.

In a chilling detail presented at trial, prosecutors said Ouchi bought a Mickey Mouse plush toy, hid the tracking device inside it, and sent it to Komatsumoto’s parents five days before the murder under the guise of a lottery prize. Komatsumoto then brought the toy to her apartment, allowing Ouchi to confirm her location.

At the time of her death, Komatsumoto was married to another man and was five months pregnant. Her husband, who had married her six months earlier, discovered her body after the attack. His statement, read during the first hearing, revealed that the couple had been planning to report Ouchi’s stalking to the police. He called for the severest punishment, stating he had lost both his wife and their unborn child. His legal counsel requested a life sentence for Ouchi.

During the trial, Ouchi’s defense team argued that he was aware of his mental health issues and had sought medical help. They maintained he had been attempting to control his impulses, suggesting a degree of diminished responsibility.

Prosecutors initially sought a 21-year prison term for Ouchi. The court’s decision to impose a 20-year sentence reflects the gravity of the premeditated murder and the profound loss suffered by the victim’s family.