No Longer Human is one of the most important works of modern Japanese literature. The novel is presented as a series of notebooks written by Ōba Yōzō, a deeply troubled man who feels incapable of understanding or connecting with other people. From childhood, Yōzō believes he is fundamentally different from those around him. To hide his fear and confusion, he adopts the role of a clown, using humor to mask his inner anxiety and alienation. As he grows older, his life becomes increasingly chaotic, marked by failed relationships, addiction, and repeated emotional breakdowns. Despite occasional moments of kindness and affection from others, Yōzō cannot escape his sense of disconnection from society. His struggles lead him into destructive behaviors and despair, as he gradually loses any hope of belonging in the human world. Often considered semi-autobiographical, the novel reflects Osamu Dazai's own experiences with depression and existential crisis. Written in a confessional and intimate style, No Longer Human is a powerful exploration of alienation, shame, and the fragile nature of identity in modern society.