I think I just found the right book by the right author! The story is divided into three parts. Part 1 is about the acquaintance between the narrator, a young man, and Sensei, a lonely man whom he admires deeply.
Part 2 focuses on the young man's relationship with his family, particularly as his father's illness has taken a turn for the worse.
Part 3 is the most heartbreaking section, featuring a confession from Sensei to the young man. In this letter, Sensei reveals his long pent-up inner pain about his past and moral darkness, beginning with the death of his parents and his uncle's betrayal. Following these traumatic events, he then met and lived in a boarding house with strangers, Okusan and her daughter. His path crossed again with his friend, known only as K, and his predicament. He suggested that K move in with him, but he soon became jealous of K's interest in their landlord's daughter. This continual strain was affecting his attitude and decisions afterward.
What I feel is that both men (Sensei and K) possess too much pride. I even grew tired of the characters. Given their youth, this behavior is quite understandable. The stories are dark and feature morally ambiguous characters. Set in the 1920s, this slow-paced narrative is deeply personal and hauntingly beautiful, exploring themes such as family, friendship, and the fragility of human behavior: depression, insecurities, guilt, and ego. I rate it 4.5 ⭐️