He turned to historical fiction in his later years, with the novel Hosokawa Garashiya fujin (1949–1950), based on the life of the famous Christian convert Hosokawa Gracia. In addition to his own writings, Morita translated the works of Fyodor Dostoevsky, Henrik Ibsen, Miguel de Cervantes, Gabriele D'Annunzio, and Giovanni Boccaccio into Japanese. Towards the end of his life, he became a self-proclaimed member of the Japan Communist Party.
