Under Kobayashi's instruction, he made the acquaintance of poet Nakahara Chūya, the critic Kawakami Tetsutaro [ja], and others who would become well known literary figures.

After graduation, he became a journalist with the Kokumin Shimbun [ja], a pro-government newspaper, but quit after one year to devote himself to the study and translation of the works of Stendhal and other European writers into Japanese.

On the recommendation of his childhood French tutor and mentor Kobayashi Hideo, he published an autobiographical short-story of his experiences as a prisoner of war entitled Furyoki (俘虜記, lit.

Considered one of the most important novels of the postwar period and based loosely on his own wartime experiences in the Philippines, Nobi explores the meaning of human existence through the struggle for survival of men who are driven by starvation to cannibalism.

In 1958, he veered from his usual subjects and produced Kaei (花影, "The Shade of Blossoms", 1958–1959), depicting an aging, naive nightclub hostess’s struggle and ultimate demise from the destructive forces of desire and wealth in the decadent 1950s Ginza.

In the late 1960s, he revisited the subject of the Pacific War and the Japanese defeat in the Philippines to produce the detailed historical novel Reite senki (レイテ戦記, "A Record of the Battle of Leyte", 1971).

He was invited to become a member of the Japan Art Academy in November 1971 but declined to join, partly, he said, on account of his former experience of soldier and prisoner of war.

Along with translations and fiction, he also devoted himself to writing the critical biographies of Tominaga Taro [ja] and Nakahara Chūya, which won the Noma Literary Prize in 1974.