At the time he was also working part-time delivering newspapers, and his inability to add often meant that his parents had to make up for the short-fall in his accounts.

In 1912, Hirotsu joined Zenzō Kasai in establishing a literary magazine, Kiseki (“Miracle”), to which he contributed short stories and translated works of foreign authors.

His literary career began with a short story published in 1917: Shinkeibyo Jidai (“The Neurotic Age”), in which he attacked the nihilism and moral decadence of contemporary intellectuals.

[1] During the 1930s he published Futari no Fukomono (“Two Unfortunate People”) and Shiji o Daite (“Embracing a Dead Child”), both objective stories, and Yamori (“Gecko”) and Nami no Ue (“On the Waves”), which belonged to the I novel genre.

In 1944, due to the danger of air raids in Tokyo during World War II, he relocated to the resort town of Atami.

In the post-war period, Hirotsu wrote a number of biographical and autobiographical works, Ano Jidai (“Those Times”), and Nengetsu no Ashiato (“The Footsteps of Time”, 1961–1963), which won the 1963 Noma Literary Prize;[1] however, he devoted 10 years from 1953-1963 writing an obsessively detailed defense of the alleged saboteurs in the controversial Matsukawa incident.

Hirotsu led a citizen's support group for the defendants, who, after twelve years in the courts, were eventually found innocent.