Fuse eventually began taking hundreds of cases per year, sometimes free of charge, in defense of these groups.

Soon after Japan surrendered at the end of World War II, Fuse resumed his practice of the law and defended numerous clients until his death in 1953.

Fuse was born in the rural Hebita Village [ja],[1][2] Oshika District (now in Ishinomaki), Miyagi Prefecture, Empire of Japan.

He was particularly moved by the philosophy of Mozi, although Fuse read widely from both Western and Eastern texts in his youth.

[2] He was baptized in the Japanese Orthodox Church, and attended a seminary affiliated with the Holy Resurrection Cathedral in Tokyo, but dropped out after three months.

[2][1][6] In his letter of resignation, Fuse described the behavior of the prosecution as "wolf-like" in a case that he worked on, in which a mother was charged with murder after killing her child and attempting and failing to commit suicide.

He defended socialist Yoshimi Yamaguchi (山口 義三) in a case on the number of cars in Tokyo.

[2] In 1911, he defended anarchist Kōtoku Shūsui, a participant in the High Treason Incident assassination plot on Emperor Meiji.

[1][2] In 1911, he wrote a paper in favor of the movement,[2][6] in which he discussed the righteous armies that resisted Japan's colonization of Korea.

He wrote that he wished to reject the comfortable and affluent life that most lawyers adopted, and instead live alongside regular people.

I heed the call of that voice, and solemnly declare a 'self-revolution'.Fuse began offering free legal consultations and lecturing on various issues on behalf of the socially disadvantaged.

[2] In July 1923, Fuse visited Korea for the first time, in order to participate in a "Summer Lecture Tour" sponsored by the newspaper The Dong-A Ilbo.

He also submitted written statements on behalf of the defence of independence activist and member of the Heroic Corps Kim Si-hyeon [ko], who was being tried in the Seoul District Court.

Immediately after the earthquake, false rumors were spread that Koreans were taking advantage of the chaos to commit crimes.

[2] In December, Fuse delivered a speech at a memorial ceremony for the massacre, in which he angrily criticized the Japanese government and police for their role in the killings.

[6] Decades later, in 1947, he wrote a book on the massacre entitled The Truth of the White Terror After the Great Kantō Earthquake (『關東大震災白色テロルの眞相』).

[2] Afterwards, he was heavily involved in the trial of the Korean anarchist Pak Yol and his Japanese partner Kaneko Fumiko, who were charged with high treason.

[6] After Kaneko died while serving her life sentence, Fuse acquired her remains and sent them to Korea to be buried.

Farmers in Korea sent representatives to Japan to consult with Fuse on the issue of Japanese colonial policies on land ownership and taxation.

He gathered evidence in support of the farmers, conducted a significant number of interviews, and gave lectures on various topics.

[1][6][2] In 1939, he was convicted of violating the Peace Preservation Law by the Supreme Court of Japan, and sentenced to imprisonment and the loss of his bar license.