Japan man, 45, allegedly kills boss over unexplained cut to year-end bonus

A 45-year-old Japanese man has been arrested on suspicion of murdering his boss in Tokyo, with investigators saying the suspect claimed his year-end bonus was cut without explanation, fuelling resentment that may have led to the fatal attack, according to Japanese media.

Alleged attack at victim’s apartment

The Metropolitan Police Department arrested Masahiro Yamanaka, a sales manager at an audio equipment-related company, on Friday (Jan. 9) on suspicion of killing company president Akihiro Kawashima, 44, at Kawashima’s apartment in Tokyo’s Ota Ward, reported The Japan Times.

Police believe Yamanaka attacked Kawashima in his third-floor apartment between about 6:40pm on Wednesday (Jan. 7) and 11:30am the following day.

According to investigators, Yamanaka told police during voluntary questioning that he sprayed insecticide into Kawashima’s face, then stabbed him with a fruit knife he had brought from home, chasing him and stabbing him from the back.

Later, during police questioning, he claimed he had meant only to threaten his boss, as cited by The Yomiuri Shimbun:

“I did stab him, but I didn’t intend to kill him.”

Kawashima was stabbed more than 10 times in the neck, stomach and thigh, and had defensive wounds on his fingers, suggesting he tried to fight back.

Bonus cut cited as possible motive

Investigators say Yamanaka told them his bonus had been reduced without explanation.

He said that his bonus had been cut from the equivalent of 1.5 months’ salary to one month’s salary, and that no reason was given.

A pay stub showing the reduced bonus, paid last December, was found at his home.

He reportedly told police that he had repeatedly voiced his workplace frustrations and was dissatisfied with his boss’s attitude.

He explained, as reported by Yahoo News Japan:

“I came to believe that if words didn’t work, I had to make him change his mind even if it meant making him suffer."

CCTV showed suspect’s movements

Security camera footage showed Yamanaka leaving his home around 5pm, entering Kawashima’s apartment building at about 5:40pm, and leaving around 7:30pm, roughly 50 minutes after Kawashima returned home.

Footprints stained with blood were found inside the apartment and on an emergency stairway.

Investigators also believe Yamanaka changed clothes before and after the killing, based on camera footage showing him in different outfits at various points.

Police say he locked the apartment door using a key found near the entrance, then pushed it through the mail slot, apparently to delay the discovery of the body.

Investigators believe that after leaving the apartment, Yamanaka met a friend at a restaurant in Ota Ward about 30 minutes later and went bar-hopping across three locations until the early hours of the morning, according to Yahoo News Japan.

The following Friday morning (Jan. 9), a day after Kawashima’s body was found, officers stopped Yamanaka as he was heading towards a Shinkansen platform at Tokyo Station.

Former classmates and close friends

Accoridng to Japan Times, Yamanaka and Kawashima had been classmates in high school and remained close for years, according to Yamanaka’s mother.

Kawashima later invited Yamanaka to join his company about four years ago, hoping he could act as a bridge between management and staff.

Before joining the firm, Yamanaka had worked in advertising. He reportedly said the new job offered better conditions than his previous work.

The two even travelled together for work, and Kawashima had reportedly cried with joy at Yamanaka’s wedding eight years ago.

Mother apologises

Yamanaka’s 72-year-old mother apologised publicly, saying her son had done “something irreparable”.

She described him as a cheerful, gentle child who disliked violence and said:

“If he had problems at work, he should have walked away.”

She regretted not being able to stop him and added that while her son must atone for his crime, “Kawashima’s life will never return”.

Police are continuing to investigate whether the killing was planned in advance, while also verifying whether the alleged bonus cut was the main trigger behind the attack.

Top images via tweetsoku1/X, Jiji.com