“I’ll Kill You, I’ll Kill You, I’ll Kill You” — What Was Really Behind the Defendant’s Claim He Had No Sexual Motive?

He maintained to the end that it was not for sexual purposes

July 29 marked the expiration of the appeal deadline for Yosuke Oka (46), who had been convicted of non-consensual indecent assault against three women. His sentence of four years in prison, against a prosecution demand of five years and six months, became final. The sentence had been handed down by Judge Satoshi Ikeda at the Chiba District Court on July 14, 2026.

The trial revealed the defendant’s disturbing methods, in which he allegedly rendered women unable to resist—either by frightening them or by giving them sleeping medication—before committing indecent acts. Yet throughout the proceedings, Oka repeatedly insisted that “I don’t remember” and “It wasn’t for sexual purposes.” What exactly did he mean by those claims? Here is a look back at the trial.

According to the indictment and other documents read out at the opening hearing on February 16, Oka committed indecent acts against a high school girl, referred to as A (16 at the time), on a train one morning in May 2025, including putting his hand under her skirt. During the assault, he threatened her from behind, saying, “I’ll kill you, I’ll kill you, I’ll kill you. I’ll kill you if you make a fuss. I’ve got a knife,” in order to prevent her from resisting.

That same month, he also allegedly assaulted B (23 at the time), whom he had met through a dating app, after putting a sleeping drug into her drink and causing her to become semiconscious. He then put his hands inside her clothing and committed other indecent acts.

It was reportedly the first time B had met Oka. They had agreed to meet in exchange for ¥10,000, and after eating at a yakiniku restaurant, Oka allegedly took advantage of the moment when B went to the restroom to put a sleeping medication he had brought in a soy sauce dispenser into her drink. They then moved to a private room at a bar, where he allegedly carried out the assault.

Then, one evening in July of the same year, he allegedly committed indecent acts against C (20 at the time) on a train, including putting his hand inside her clothing. He also threatened C, reportedly telling her, “I’ll kill you.”

Oka acknowledged the charges in each case, saying “There is no mistake.” However, this meant that he acknowledged that he was the person shown in the security camera footage of the incidents, while maintaining that because of the effects of the sleeping medication I was taking, I have no memory of the incidents, or there are parts I cannot clearly remember.

Oka explained that he suffered from a sleep disorder and claimed that “I’ve been taking sleeping medication for nearly 20 years.”

He gave her sleeping medication because he wanted to hear what she really thought

Why did Oka allegedly go on to commit a series of disturbing offenses?

At trial, the first thing Oka complained about was the harsh working environment at the restaurant where he had been employed at the time.

“My direct supervisor was working more than 200 hours of overtime a month, and I myself hardly had any days off. I also suffered a fracture that required three months to heal while I was at work, but even though I was living with my arm or leg in a cast, I couldn’t take time off. Because the company showed no consideration whatsoever, I became extremely distrustful of it and was under tremendous psychological pressure.”

His relationship with his mother, with whom he was living at the time, was also poor. He said there was nowhere I could relax, and I gradually started taking larger amounts of sleeping medication. I was often in a dazed state.

As for why he claimed not to remember the assaults against A and C, Oka described his condition at the time:

“There were times when I would wake up in the morning and find large amounts of food that I had no recollection of buying, or suddenly realize that I was somewhere I had absolutely no idea about. I also have only fragmentary memories of this, but there were times when I got into fights on trains.”

According to Oka, because I had taken large amounts of sleeping medication, there were times when I would act without being conscious at all. He claimed that he assaulted A and C while in such a state, and therefore maintained that the acts were not committed for sexual purposes.

However, he said he had fragmentary memories of what happened with B. He recalled that there had been a particular reason for putting sleeping medication in her drink:

“When you give someone sleeping medication, it’s interesting because they become unable to lie and you can see what they really think. In the past, I secretly gave it to male coworkers at work as well. To put it badly, I was just playing around.”

When his defense attorney asked, “Why did you want to know what was really on B’s mind?”, he answered:

“It’s the same with me, but on dating apps, things like people’s jobs and backgrounds in their profiles are often made up or inaccurate. I was curious to see how their stories would change after taking the medication, and whether their true feelings would come out.”

Oka then claimed that after B took the sleeping medication, she revealed her true feelings that she was interested in men’s bodies, and that this led to his subsequent actions.

He therefore maintained that giving B the sleeping medication was not done with sexual intent, but rather out of curiosity about hearing her true thoughts.

He also said he had hatred toward girls

Upon hearing this, the prosecutor, seemingly angered, removed his glasses and placed them on the desk before questioning Oka in a stern tone.

Prosecutor: “You said you decided to give her the medication because you wanted to hear what she really thought. Do you think anyone would actually believe that?”

Oka: “Well, that’s genuinely how it was for me, so that’s all I can say.”

Prosecutor: “What I’m asking is whether you think anyone would hear that explanation and say, ‘I see,’ and actually believe it.”

Oka: “I suppose there aren’t many people who would.”

Prosecutor: “Not many? Do you think there is even one person who would?”

Oka: “I suppose there might be.”

Oka also said that one of his motives for committing indecent acts against A and C on trains was that “I was sexually victimized by a high school girl in the past, and because of that trauma, I came to hate high school girls.”

According to Oka, C, who was 20 at the time, looked younger than her actual age, and he suggested that while in an unconscious state, he may have perceived her as a high school student. He claimed that he wandered around while unconscious and sexually assaulted a woman who appeared to be a high school girl as an act of revenge.

Throughout the trial, Oka stubbornly continued to deny that he had committed the offenses with sexual intent. In the closing arguments, the defense argued that three years and six months in prison would be an appropriate sentence, noting that a settlement had been reached with A. However, Oka chose not to appeal and accepted the verdict.

In his final statement, Oka apologized to the victims. He also said that during his detention, he had managed to stop taking sleeping medication and had repaired his relationship with his mother. He said, “I want to use this as an opportunity to live an honest life from now on.”

Whether he will truly be able to return to society after serving his sentence and live an ordinary life without committing another offense remains to be seen.