Harukichi Inoue was born in Fukuoka Prefecture in 1883 to a former samurai. After completing middle school, he moved to Tokyo, where he enrolled in the English Department of the Higher Normal School. In 1907, he was adopted by Kisuke Shimoi, a lumber merchant and architect, from whom he took the surname and whose daughter he later married.

He went on to become a poet and a teacher at a girls’ school while continuing his studies. After reading The Divine Comedy in Japanese, he was so deeply impressed by Italian culture that he decided to learn the language at the University of Foreign Studies. In 1911, he chose to move to Italy to study Dante and settled in Naples, where he met several intellectuals of the time. In 1915, he became a professor of Japanese at the Oriental University Institute.

Two years later, he volunteered as a war correspondent and, at the front, met General Armando Diaz and the poet Gabriele D’Annunzio. Soon after, he decided to enlist as a soldier, becoming an Ardito and taking part in several key battles, including the Battle of Vittorio Veneto. After the war, he followed D’Annunzio in his occupation of Fiume, during which the poet himself honored him with the title “Samurai Comrade.” At the same time, Shimoi facilitated correspondence between D’Annunzio and Mussolini.

During this period, Shimoi grew to admire the future Duce, seeing in him a man of action who embodied the nation’s “vital force,” capable of renewing a decaying society and leading Italy toward a “warrior order.” He also perceived similarities between Fascist ideals and the bushido, the samurai code, particularly in discipline, loyalty, sacrifice, and the supremacy of community over the individual.

His friendship with Mussolini became so close that he joined the March on Rome. After the rise of Fascism, Shimoi served as a cultural and political intermediary between Italy and Japan, strengthening bilateral relations. He promoted Italian culture and Mussolini’s image in Japan while introducing Japanese writers and judo to Italy.

In the 1930s, he returned to Japan and began to distance himself from both the Italian and Japanese governments because of their alignment with Hitler, whose racial ideology he despised. Nevertheless, he never renounced his early admiration for Fascism and remained the Tokyo correspondent for Corriere della Sera until 1943.

After World War II, Shimoi retired from public life and met journalist Indro Montanelli, whom he guided through his homeland before passing away in 1954.