do not widely document details of his early life, family background, or personal history prior to the events of 1949. Takeuchi was employed by the Japanese National Railways (JNR) and worked in the railway system during a period of post‑World War II reconstruction and intense political tension in Japan. Amid widespread labor unrest and disputes within the rail industry and against the backdrop of occupation policy shifts, several major railway incidents occurred in 1949. Takeuchi’s story is most prominently tied to one of these events, the Mitaka incident, which would define the rest of his life.

On the evening of 15 July 1949, an unmanned 63 series passenger train operated by the Japanese National Railways was released on the Chūō Line toward Mitaka Station in western Tokyo. The train, with its operating handle supposedly tied down, traveled without a crew and crashed through track‑end barriers at Mitaka Station, causing a derailment that killed six people and injured around 20 others. The cause of the derailment was immediately controversial, and the incident became one of Japan’s most enduring railway mysteries.

In response to the tragedy, Japanese authorities charged ten railway workers with sabotage resulting in death. Among them was Keisuke Takeuchi, who was uniquely singled out as the principal perpetrator despite not being aboard the train when it derailed. Prosecutors alleged that Takeuchi planned and executed the act himself.

During pre‑trial proceedings, defense testimonies  including statements that Takeuchi and a coworker were together at a public bath at the time the train left the station  were reportedly not accepted by the court. Such evidence, argued by some historians to be potentially exculpatory, was excluded by Takeuchi’s counsel.

In 1955, the Japanese judicial system, including the Supreme Court, upheld Takeuchi’s conviction on charges related to sabotage and mass death, and he was sentenced to death. He maintained his innocence throughout the lengthy legal process and subsequent imprisonment, asserting that his earlier confession was obtained under coercion. Reports later suggested that the confession may have been extracted under duress by police.

All co‑defendants nine other accused individuals were acquitted when the court found no substantiated evidence of a broader conspiracy. Many of these acquitted men were members of the Japanese Communist Party, while Takeuchi himself was not affiliated with the party.

Takeuchi spent the remainder of his life incarcerated. He died in detention on 13 January 1967 from a brain tumour at the age of about 45. At the time of his death, he had never been executed; his death effectively commuted his sentence in practice. Until the end, he continued to assert his innocence.

Decades later, legal efforts persisted to revisit his conviction. In 2019, the Tokyo High Court denied a retrial request, and on 17 April 2024, Japan’s Supreme Court likewise rejected a special appeal seeking to reopen the case. Despite these rulings, Takeuchi’s eldest son filed for a third retrial on 5 September 2024, signalling continuing family efforts to clear his father’s name.