Born on June 19, 1909, the sixth son of the great landlord and House of Peers member Tsushima Gen'emon in Kanagi village, Kitatsugaru District, Aomori (today Kanagi-cho, Goshogawara City). His real name was Tsushima Shuji. Raised in the mansion 'Shayokan' (today the Dazai Osamu Memorial Hall), after old-system Hirosaki Higher School, in 1930 he entered the French Literature Department of the Faculty of Letters, Tokyo Imperial University (withdrew in 1935). In his life he experienced four suicide attempts: his first in November 1930 (a love-suicide with the waitress Tabe Shimeko at Koshigoe, Kamakura, where only the woman died), his second in March 1935 (an attempted hanging on the hill behind Kamakura Hachiman-gu), his third in March 1937 (an attempted lovers' suicide at Minakami Onsen with his common-law wife Koyama Hatsuyo), and his fourth in June 1948 (a successful drowning-suicide with his lover Yamazaki Tomie in the Tamagawa Canal). He also suffered from drug and alcohol addiction. In 1939, with Ibuse Masuji as go-between, he married Ishihara Michiko, and in a relatively stable period he wrote 'A Hundred Views of Mount Fuji,' 'Run, Melos!' (1940), 'Tsugaru' (1944), 'The Setting Sun' (1947, depicting the fallen nobility of the postwar period, winning women fans and making 'shayo-zoku' a popular term), 'Villon's Wife' (1947), and others. After the war, together with Sakaguchi Ango and Oda Sakunosuke, he was called part of the 'Buraiha' and 'Shin-gesakuha,' forming a new current in postwar Japanese literature. In March-May 1948 he wrote 'No Longer Human' (serialized in the coterie magazine 'Tenbo,' June-August issues), his representative work. Late on June 13, 1948, together with Yamazaki Tomie he drowned in the Tamagawa Canal in Mitaka, Tokyo; the body was found on June 19 (strangely, his 39th birthday). His grave is at Zenrin-ji in Mitaka.