- His real name is Tsushima Shuuji.
- He was the eighth surviving child of large landholder's family. Though his family's holdings were initially humble and in a very remote region of Japan, after his birth they gained significant wealth and political power.
- When he was in school, he would often walk home with a boy he had a crush on. Once the boy gave him a newt, and Dazai, who hated newts, accepted it as though he were delighted.
- He would use playing cards to predict his fortune for the day. Hearts were the best suit to draw, diamonds were next, clubs were ominous, and spades meant total disaster.
- He idolized Akutagawa Ryuunosuke and was shaken by his suicide. Though he had been a diligent student before, he began to neglect his college studies, and made his own first suicide attempt before his final exams.
- He seemed to find the idea of double suicide romantic, as most of his attempts were made with a lover - one even with his own wife at the time after she committed adultery. When neither of them died after taking sleeping pills, he divorced her instead.
- He attempted to commit suicide 5 times in total. He finally succeeded in killing himself by drowning together with his mistress; their bodies were found on June 19, 1948, his 39th birthday.
- He was cut off from his family a few times. The first expulsion was in response to him running away with a geisha, and a few days later he tried to drown himself with another young woman. She died, but he was rescued by a passing fishing boat and charged as an accomplice in her death. His family intervened, had the charges dropped, and reinstated his allowance. They briefly cut him off again for affiliation with the then-banned Japanese Communist Party, but when his elder brother promised to have those charges dropped and reinstate his allowance if he swore not to have any further involvement with them, he took up the offer.
- He desperately wanted the Akutagawa Prize for Pure Literature - partly because Akutagawa Ryuunosuke was his idol, partly for the prize money and recognition - to the point he once prostrated before his mentor Satou Haruo, who was also one of the judges, to beg for the Prize.
- The first time he was nominated for the Akutagawa Prize, he had been confident in winning. In the end, the reason for his defeat was the opinion of one of the judges, Kawabata Yasunari. Afterwards, he wrote an open letter that can be considered an attack against Kawabata.
- He died at the age of 38 years old.