He published his first novel, Hatsusugata, a story about a geisha and her relationship with men from different social strata in 1900. He followed with a sequel, Hayariuta, in 1902, which was one of his most successful works. Kosugi attempted to write in a realistic and objective manner, without intruding the thoughts or comments of the author into the story narrative, which was considered rather revolutionary for the time.
In 1900, he penned his first novel, Hatsusugata, centered on a geisha’s experiences with people from various social classes. He later released Hayariuta in 1902, which was one of his most popular works. Kosugi sought to write in a realistic and detached manner, refraining from inserting personal opinions or commentary into the story, an approach that was particularly innovative for its era.