Murder of the Sakamoto family

Tsutsumi Sakamoto was a lawyer with the Yokohama Bar Association who, from 1987, worked at Yokohama Law Offices. He had earlier led a successful class-action suit against the Unification Church on behalf of members' relatives, and by the late 1980s he had turned to Aum Shinrikyo, a Japanese doomsday cult. In 1988 he helped establish a group to assist people affected by Aum, later known as the Aum Shinrikyo Victims' Association, and he prepared a class action arguing that members had been drawn in by deception and that the group used high-pressure "spiritual sales" to drain money from followers' households. A judgment in his clients' favour could have bankrupted the organisation.

In October 1989, Tokyo Broadcasting System Television (TBS) recorded an interview with Sakamoto about his anti-Aum work. The network secretly showed the footage to Aum members and, under pressure from cult officials, cancelled the planned broadcast.

On November 3, 1989, several Aum members drove to Yokohama intending to abduct Sakamoto at a Shinkansen station, carrying hypodermic needles and potassium chloride, but he did not appear because of a public holiday. In the early hours of November 5, the group entered his apartment through an unlocked door. Sakamoto, his wife Satoko, aged 29, and their 14-month-old son Tatsuhiko were killed. The family's remains were sealed in metal drums and concealed in rural parts of three separate prefectures — Niigata, Toyama, and Nagano — a distribution intended to keep investigators from linking the cases.

For six years the family's whereabouts remained unknown. According to NHK, Tokyo police received a tip in 1991 and briefly investigated Aum facilities, but closed the inquiry after two months because the crime fell outside their jurisdiction. The cult's involvement was established only after senior members were arrested in connection with the 1995 Tokyo subway attack; the perpetrators then revealed the burial sites, where the skeletal remains were recovered.

Police charged four Aum members with the murders. One of them, chief scientist Hideo Murai, was killed during a police transfer in April 1995 before he could be tried. Kazuaki Okazaki pleaded guilty and was found guilty in October 1998; Tomomasa Nakagawa and Satoro Hashimoto were convicted in 2000. On July 25, 2000, the three were sentenced to death, and on July 28, 2000, Kiyohide Hayakawa was also sentenced to death for his role. A court found that the killings had been ordered by the cult's founder, Shoko Asahara, who denied involvement.

Nakagawa was executed on July 6, 2018, and Okazaki and Hashimoto on July 26, 2018. In 2017, Nakagawa had published a prison memoir renouncing his Aum beliefs and apologising to the victims' families. After TBS's role in exposing Sakamoto to the cult became public, the broadcaster faced widespread criticism and its president resigned.