See J. A. Walker, The Japanese Novel of the Meiji Period and the Ideal of Individualism (1979).
Tōson graduated from Meiji Gakuin University in 1891, and became interested in literature through his friendship with essayist and translator Kochō Baba (馬場孤蝶 Baba Kochō) and Shūkotsu Togawa (戸川秋骨 Togawa Shūkotsu). He joined a literary group associated with the literary magazine Bungakukai (文學界) and he also began to contribute translations to Jogaku Zasshi (女学雑誌 Magazine of Women's Learning).
He moved from Tokyo to Sendai in northern Japan to accept a teaching position, but continued to write as a hobby. His first verse collection, Wakanashū (若菜集 Collection of Young Herbs, 1897) was published while he was in Sendai and launched him on his future career.
However, around the same time, Tōson was discovered to be having an affair with one of his female students, which led to his resignation from the school. The suicide of his close friend, the Romantic writer Kitamura Tokoku, also came as a great shock and Tōson moved back to Tokyo.
His first novel, The Broken Commandment was published in 1906. It was considered a landmark in Japanese realism and is thus regarded as the first Japanese naturalist novel. It is a story of a burakumin schoolteacher, who keeps his out-caste status secret until near the end of the story. While he was writing, each of his three children died of illness.
His second novel, Haru (春 Spring, 1908) was much weaker and is a lyrical and sentimental autobiographical account of his youthful days with the Bungakukai.
His third novel, Ie (家 Family, 1910-1911) is considered by many to be his masterpiece. It depicts the slow moving decline of two provincial families to whom the protagonist is related.
Tōson created a major scandal with his next novel, Shinsei (新生 New Life, 1918-1919). A more emotional work than Ie, it is an autobiographical account of his own extramarital relations with his niece, Komako, and the knowledge that her father (his elder brother) knew of the incestuous affair, but concealed it. When Komako became pregnant, Tōson fled to France to avoid the confrontation with his relatives, abandoning the girl. Tōson attempts to justify his behavior by revealing that his father had committed a similar sin and that he could not avoid the curse of his lineage. The general public did not see it that way and Tōson was censured on many fronts for his behavior and for what was perceived as a gross vulgarity by attempting to capitalize on the disgraceful incident by turning it into a novel.
On his return to Japan, Tōson accepted a teaching post at Waseda University. He then wrote Yoakemae starting in 1929, a semi-historical novel about the Meiji Restoration from the point of view of a provincial loyalist, who is a thinly veiled representation of his father. Written unevenly, the protagonist dies in bitterness and disappointment. It was serialized in the literary magazine Chūōkōron over a six-year period and was later released as a two-part novel.
In 1935, Tōson became the founding chairman of the Japanese chapter of the International PEN organization. Tōson died of a stroke at the age of 71, in 1943. His grave is at the temple of Jifuku-ji, in Oiso, Kanagawa Prefecture.