Kenichi Hosoya and his wife, Shiho, are arrested on suspicion of murdering their 4-year-old daughter with poison in Tokyo’s Taito Ward on Feb. 14. (The Adahi Shimbun)

Photo/Illutration Kenichi Hosoya is arrested over the death of his daughter in Tokyo’s Taito Ward on Feb. 14. (Shigetaka Kodama)

Tokyo police on Feb. 14 arrested a couple on suspicion of murdering their 4-year-old daughter by forcing her to drink poison over a prolonged period.

Yoshiki Hosoya, the youngest daughter of Kenichi Hosoya, 43, and his wife, Shiho, 37, was confirmed dead after she was taken to a hospital emergency room in Tokyo around 9 a.m. on March 13, 2023.

The father had called the 119 emergency number, saying Yoshiki was not breathing.

An autopsy showed the cause of the girl’s death was poisoning. There were also indications that Yoshiki had long suffered from abuse and neglect.

Kenichi has denied the allegations, saying, “I am not involved,” while Shiho has remained silent, police said.

According to investigative sources, Kenichi’s older sister died under suspicious circumstances in April 2018 at the age of 41. The Metropolitan Police Department is investigating whether the two deaths are related.

Although there were no significant external injuries on Yoshiki’s body, the autopsy showed she had consumed olanzapine, an antipsychotic drug, and ethylene glycol, which is mainly used for industrial purposes, such as antifreeze.

There were no medical records showing the girl needed to take olanzapine, the sources said.

On Aug. 29, police searched the couple’s home in Tokyo’s Taito Ward and interviewed them on a voluntary basis. They confirmed the couple had bought olanzapine and ethylene glycol on the internet, the sources said.

Based on an analysis of Yoshiki’s hair, it was determined she may have ingested olanzapine for a prolonged period before her death.

Police also determined the possibility of accidental ingestion of the chemicals was low.

According to the sources, the couple married in 2009.

In recent years, they have lived with their three children in a room located on the top floor of a 10-story apartment building about 500 meters from Sensoji temple.

Yoshiki was the youngest child, born in January 2019.

Two months after the girl’s birth, Shiho was questioned by police after she was seen setting fire to clothes on the balcony of the family’s apartment room, according to the sources.

At that time, police notified a child guidance center that the three children in the Hosoya family were in danger of being abused, and that they should be temporarily taken into protective custody.

Yoshiki had been sent to several kindergartens and nursery schools. Some preschool officials told police that Yoshiki wore the same clothes every day and sometimes smelled of excrement.

Her hair was matted and tangled in bunches, and she may not have been allowed to change or bathe properly, according to the sources.

After the police search in August, the two remaining children began living apart from the couple.

Kenichi’s mother died in January 2018, and his older sister died in April 2018.

According to a registry, Kenichi replaced his father as president of a hotel management company on June 1, 2018. Four days later, the father died.

The following month, Shiho became a director of the company.

(This article was written by Yuji Masuyama, Minami Endo and Shomei Nagatsuma.)

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