Omori Apartment Boss Murder Case Shifts Toward Robbery-Murder Theory Three Months After Arrest

The person arrested on January 9 on suspicion of murdering K, who ran an audio equipment company and was 44 at the time, was Yamanaka Masahiro (then 45), an employee of the victim and also his high school classmate. The incident took place in a room at an apartment in Omori (Ota Ward), where K lived, and was discovered around 11:30 a.m. on January 8.

《“A acquaintance who visited the apartment because K did not arrive at a scheduled meeting called the police. Officers found K lying in a room covered in blood. He had been stabbed in multiple places, including the neck and abdomen, and had injuries on both hands believed to have been caused while resisting.

Bloodstains and bloody footprints were found in the hallway and entrance, and since the murder weapon was not found in the room, the Metropolitan Police Department’s First Investigative Division determined it to be a homicide and set up a special investigation headquarters at Omori Police Station,” said a reporter from a national newspaper’s social affairs department.》

At this point, it was Yamanaka who handed over the spare key to K’s apartment—entrusted to him by a company colleague—to officers from Omori Police Station who arrived after the emergency call. He also underwent questioning that day and remained cooperative throughout, while denying any involvement in the incident.

However, because some parts of his statements were vague, police had reportedly suspected Yamanaka from the beginning. While he was under surveillance, he left his home early on the 9th and was seen attempting to purchase a Shinkansen ticket at Tokyo Station, leading to voluntary accompaniment and his arrest the same day.

Yamanaka stated, “I had dissatisfaction with K’s usual behavior and went to his home to confront him. He became enraged, we got into a struggle, and I stabbed him with a fruit knife I had brought from home.” He also said, “I sprayed insecticide at the entrance, and when he hesitated I stabbed him in the neck. I chased him as he tried to escape and attacked him from behind.” He admitted to stabbing K but partially denied intent to kill, saying, “I did not intend to kill him.”

K and Yamanaka were boss and subordinate at work, but also high school classmates and friends of 30 years. They were close enough to call each other by nicknames and often went drinking and traveling together. K had even attended Yamanaka’s wedding about eight years earlier. However, after K invited Yamanaka to join his company and work together, their relationship gradually changed. The article at the time included the following testimony:

《“They reportedly stopped appearing together at the bars they used to frequent. Yamanaka’s mother also said he seemed dissatisfied with his job, and he himself stated that he was unhappy about a lack of appreciation toward employees and rude language. He said that because his complaints were not understood, he came to think that ‘if they don’t understand through words, it may be necessary to make them understand by making them suffer.’

He also stated, ‘My bonus, which had been 1.5 months’ worth, was reduced to one month,’ and ‘No reason was given.’” (incident writer)》

At the time, Yamanaka denied intent to kill, saying, “I did not intend to kill him” and “I brought the knife only to threaten him.” However, it has since become increasingly clear that there were aspects suggesting the crime may have been premeditated.

“The security camera at the scene is believed to have captured Yamanaka appearing two days before the incident as well, suggesting he may have been conducting prior reconnaissance. It is also noted that on the day of the incident, Yamanaka changed clothes between before and after the crime. There were bloody footprints in K’s bathroom and dressing area, indicating he may have washed his body after the attack.

Furthermore, when leaving the room, he is believed to have locked the door using K’s own key, possibly in an attempt to delay the discovery of the body. The key was apparently placed in the mailbox and was later found inside the front door.

After that, he traveled by taxi and disposed of the clothes worn during the crime and the knife in a plastic bag at the garbage area of an apartment building in Ota Ward where he had previously lived,” said a reporter from a national newspaper’s social affairs department.

Yamanaka was indicted on January 29 on charges of murder. However, the case then took an unexpected turn. On April 8, prosecutors requested a change of charges to robbery-murder at the Tokyo District Court. After the amendment, the indictment alleged that Yamanaka stabbed K to death after borrowing 440,000 yen from him, and in addition to avoiding repayment of the debt, stole approximately 160,000 yen in cash.

“During interrogation, it became clear that Yamanaka had borrowed money not only from K but also from other acquaintances. It also appears that cash was missing from K’s wallet found at the scene,” said the same source.

Was the motive for killing a friend of 30 years not workplace resentment, but money?

As of May 1, the trial schedule had not yet been decided.