Episode 104:
High School Teachers' 4-Year Secret Affair, Then One Vanishes

On May 30, 2022, a report was phoned in to a police station in Hokkaido, Japan. "My wife said she was going to Kushiro yesterday morning, but I still can't get a hold of her. The kids are at home! This is just... insane." Somehow, the husband's tone was filled more with annoyance and anger than worry for his wife.

The missing woman was forty-seven-year-old high school teacher Mako Miyada — a devoted mother, a well-liked educator known for going out of her way to help struggling students, and by every outward appearance, the picture of an ideal working parent.

Contrary to her reputation, Mako had spent four years hiding an affair — and, strikingly, her husband already knew about it. When he called police, he said with total certainty: "I'm telling you, she's with that guy. His name's Shuri Katagiri. Just tell her to go live with him." Police traced Mako's last known location to Obihiro, a town 130 kilometers from her home — and the city where her lover lived.

Four Years, Two Marriages

The affair began in April 2016, when Mako transferred to a new school and quickly became one of its most popular teachers — rivaled only by thirty-five-year-old Shuri, a former aspiring baseball player turned beloved teacher known for going out of his way to support struggling students. Both were married with no history of trouble, but Mako, twelve years his senior, made the first move, and Shuri later described himself as feeling "under a spell." The two began meeting in hotel rooms, keeping the relationship so well hidden that not a single colleague at their school ever suspected it, sustaining the affair from 2018 to 2022.

Shuri, who had no children with his wife at the time, reportedly told Mako he wanted to divorce and build a life with her — words that convinced her their relationship was real and permanent. She eventually told her husband everything, intending to divorce and start over with Shuri, and began seeing him openly. Then she disappeared.

The Forest Outside Obihiro

Police went to Shuri directly, who claimed he and Mako had broken up at the start of the year and that he'd since transferred schools and hadn't seen her. Brought in for formal questioning, he immediately invoked his right to silence. Two days into the investigation, on June 1, he abruptly changed course and led police to a small forest outside Obihiro, where they found Mako's partially burned cell phone and driver's license — and, at a spot Shuri pointed out, her body buried in a shallow grave.

By Shuri's account, the affair had been souring for roughly three years — he had never intended to leave his wife and had simply been enjoying the thrill of it, losing interest after about a year and asking to end things, while Mako refused, insisting she truly loved him and threatening to expose the affair at school if he pushed too hard. The turning point, he said, came when his wife became pregnant with their first child; determined to end it for good, he found Mako unwilling to let go and, according to him, escalating into threats involving his wife and new daughter.

A Price for Silence

In 2021, Mako allegedly proposed a transactional exit: pay her $45,000, and she'd walk away and never speak of the affair again. Distrustful but desperate, Shuri paid roughly half — and, as he'd feared, she said it wasn't enough and refused to end things regardless. The affair dragged into 2022, when Shuri finally caught what seemed like a lucky break: a transfer to Obihiro High School, 130 kilometers from home, followed shortly after by Mako transferring schools as well.

On his very first day at the new school, he received an urgent call — Mako, warning him she'd expose the affair to his new colleagues if he thought distance would let him escape her, alongside roughly 600 missed calls on his phone. She began calling daily and showing up at his school. Under mounting pressure, Shuri begged her on his knees to end things; her price this time was the remaining balance of the money, which he says he paid, believing it would finally be over. It wasn't.

The Final Confrontation

On May 29, the day of the murder, Mako lied to her husband and drove to Obihiro, waiting near a stadium during a high school baseball game for Shuri to appear. According to Shuri, he told her again it was over; she refused to accept it and forced herself on him before he pulled away and fled to the school, with Mako following and staking out his car late into the night. He slipped out the back and took a taxi home, only to find his car ransacked the next morning — Mako had used her spare key to search it, and discovered his COVID vaccine card listing the new address he'd been hiding.

His phone rang moments later — Mako, parked outside his house. When he got into her car, she reportedly delivered an ultimatum: divorce his wife immediately or she'd kill both his wife and daughter. Shuri talked her into relocating to a quieter parking lot to "discuss it" — and, by his account, decided during the drive that the only way to protect his family was to end her life. He proposed a suicide pact instead, telling her they could "die together" and be together in the next life; she agreed without resistance. In the back seat, he wrapped a seatbelt around her neck and strangled her for ten minutes until she stopped moving.

Business as Usual

Shuri claimed he changed his mind about dying alongside her once he saw her body, deciding he wanted to live for his family instead — leaving him with a corpse to dispose of. He drove her car back to his house, moved her body into his own trunk, and slept. The next day, a Monday, he went to work and coached the baseball team late into the evening as usual, his car with Mako's body in the trunk parked in the school lot the entire time. That night, he drove into the forest, burned her phone and license, and buried her.

It's worth remembering that this entire account comes solely from Shuri — with Mako dead, there was no way to verify any of it, and the story conveniently framed him as a cornered victim rather than a man who continued a four-year affair, including ongoing intimacy, long after he claimed to have lost interest. Investigators themselves suspected the narrative was shaped to minimize his sentence.

Final Thoughts

At his first trial, Shuri argued the killing was a consensual death pact, deserving a lighter sentence, and his lawyers claimed his mental state had collapsed under Mako's demands and obsession, requesting just three years with five years' probation. Prosecutors rejected the "consent" framing entirely, noting it rested on nothing but Shuri's word, and pushed for a standard murder conviction. The first trial nonetheless accepted the consensual-killing framing and sentenced him to six years and six months — a decision prosecutors immediately appealed. In February 2025, the appellate court overturned the verdict, convicting Shuri of murder outright, ruling that strangling someone for more than ten minutes demonstrated clear intent to kill, and sentencing him to twelve years.

Because the case relied so heavily on Shuri's own testimony, public reaction skewed toward viewing Mako primarily as an obsessive stalker rather than a victim, with some expressing outright sympathy for her killer. The people left most exposed by the case were Mako's own children, labeled by association as "children of a cheater," and her husband, whose own choices before her death became a matter of public commentary. Neither the affair nor its ending offered anyone in the story a way out that didn't end in devastation.