Abstract: This presentation examines the connections between Japanese Naturalism and the first trend of Japanese Marxism (1920s to 1933), centered in Kurahara Korehito (1902-1999). In Kurahara Korehito’s 1928 essay, “The Way to Proletarian-Realism,” he famously asserted that the fundamental difference between Naturalism and proletarian literature lied in the way in which they conceived of the relationship between individual and society. The individual represented in Naturalism is isolated from society, Kurahara criticized. Following Kurahara the Japanese Marxists endeavored to establish Marxism as a social science, and, to a certain extent, have succeeded. But the movement remained at odds with the natural sciences, in particular with the established notion of humanity in Japan at the time. Questions of humanity remained unanswered at the center of the Marxist discourse in Japan: is there a human essence? What is the relation between man and nature?