Episode 110:
A Teacher's Twisted Obsession

9:00 a.m., December 10, 2005. At an ordinary cram school in Kyoto, Japan, police came rushing in, headed straight for classroom 106. The door was locked tight. Holding their breath, officers peered through a gap in the window blinds and saw a man standing in front of the chalkboard, his expression completely blank. Something was terribly wrong. When they ordered him to open the door, he slowly complied and stepped outside — revealing a scene behind him that was beyond horrific.

The classroom looked like a slaughterhouse. Desks and chairs were overturned everywhere, the floor so drenched in blood there was nowhere to step. In the corner, slumped against the wall, was a small girl — her face, head, and neck covered in stab wounds, both arms marked with defensive injuries so severe that two of her finger joints had been severed and were lying on the floor. Nearby lay the weapons: two bloody kitchen knives and a hammer.

The Creepy Teacher

The victim was twelve-year-old Sayano Horimoto, a bright, exemplary student — gifted at math, good with her hands, well-liked by her friends. The autopsy found the cause of death was a fatal stab wound to the right side of her neck. The killer was twenty-three-year-old Yu Hagino, a cram school instructor — and chillingly, the one who had called the police himself. He was arrested on the spot, and the motive he gave investigators was almost absurdly petty: he'd killed her because she'd called him "creepy."

She wasn't the only one who thought so. Hagino started at the cram school in November 2003 and was initially popular for his energetic teaching style, but his true nature soon surfaced — an unhealthy obsession with students and a habit of inappropriate touching. He showed blatant favoritism toward certain girls, grabbed their hands during class, and once persistently pursued a ninth-grader, telling her "I like you, let's date," until she quit the school just to escape him. Students eventually started openly booing him in class, and he became known as "the creepy teacher."

An Hour and Twenty Minutes of Gaslighting

His attention fixed on Sayano about two months after she enrolled, in May 2005. He called her in for a private "supplementary lesson," then pivoted to invasive personal questions — how's school, do you get along with your dad. When she gave neutral answers, his demeanor shifted; he claimed to have studied psychology and told her he could "see right through" her lies, pressuring her with relentless questioning for an hour and twenty minutes in what amounted to a calculated gaslighting session.

Sayano's parents found out and went to the school to protest. Instead of firing Hagino, the school gave him nothing more than a warning. Emboldened, his behavior escalated — standing uncomfortably close behind her during breaks, leaning in until their faces nearly touched during private meetings, and humiliating her in front of the whole class over trivial mistakes whenever he sensed her pulling away. On November 21, Sayano finally refused to attend his classes at all, and only then did the school bother rearranging schedules to keep them apart — not remove him. Other teachers reportedly already knew he was harassing female students and said nothing.

A Perfectly Calculated Murder

On December 10, the day of a mock middle school entrance exam, the director — as a precaution — pulled Hagino off proctoring duty specifically to keep him away from Sayano, a sixth grader taking the exam that day. Hagino showed up anyway, despite not being scheduled to work, and calmly asked the proctor to take the other students next door so he could "speak with Horimoto" alone. The proctor, suspecting nothing, agreed. The classroom door closed, then clicked locked.

Hagino pulled a kitchen knife from his jacket. Sayano backed away, scrambling for the corner of the locked room with nowhere left to hide — the overturned furniture a record of her final, desperate moments. He cornered her and stabbed her more than a dozen times in a frenzied attack to her face, head, and neck. No one else at the school noticed anything wrong, because the day before, Hagino had quietly unplugged the security cameras monitoring that classroom, leaving nothing on the office monitors. He had bought the knife a week in advance and prepared the hammer the day before. This had been planned.

A Household of Suppression, a Pattern Ignored

Hagino was the only child of a corporate executive father and a mother who taught Tai Chi, raised under suffocating restriction — no snacks, no TV, no video games, no friends, no dating, nothing that could distract from academics. He got into a prestigious university's law school, meeting his parents' expectations exactly — and once he became an adult, all that suppressed rage exploded, first against his own family, violently enough that his mother once had to be taken away by ambulance. In June 2003, he was caught stealing a female student's wallet at the university library, assaulted the guard who tried to stop him, and was found to have committed more than twenty campus thefts. He received a suspended sentence and was suspended from the university — and the very next day, hid his criminal record and got hired as an instructor at the cram school where he would later kill Sayano. The school never checked his background.

Sayano had cried out for help repeatedly. Her parents had complained repeatedly. The school's response, every time, was complacency — right up until it cost a twelve-year-old her life. Her family later won a civil suit against the school for roughly $1 million in damages, and her father found a way to channel his grief by volunteering to help keep other children safe on their way to and from school.

Final Thoughts

At trial, Hagino abandoned his original "she called me creepy" motive and instead claimed Asperger's syndrome, insisting he'd suffered eight days of visions of Sayano attacking him with a knife before the murder and had acted under the control of delusions. Prosecutors and experts pushed back hard, pointing to the disabled cameras and the week-in-advance weapon purchase as proof of clear premeditation, and sought a life sentence. The first trial agreed the crime was premeditated but credited his self-turn-in, sentencing him to eighteen years. On appeal, the Osaka High Court reversed course on March 24, 2009, ruling — based on a psychiatric evaluation — that Asperger's syndrome had diminished his capacity, and cut his sentence to fifteen years, citing supposed remorse. He served his time and was released in 2021. Now in his mid-forties, he is presumably living the ordinary life that Sayano Horimoto never got the chance to have.