The Narrator is an unnamed university student living in Tokyo. He straddles the line between traditional rural Japanese society, represented by his parents in the countryside, and the modernizing urban world of the city. Naïve but eager for knowledge, he is unpracticed in romance and social intricacies. He prefers intellectual stimulation and unconventional mentorship over standard academic study or practical career paths.

Sensei is an older, highly educated man living a quiet and seemingly idle life in Tokyo. Despite his sharp intellect and academic background, he holds no formal job and maintains a profound emotional distance from everyone around him. He carries a dark past that heavily influences his mistrust of the world. He chooses to visit a specific grave every month while refusing to allow anyone to accompany him.

K is an intense, intellectually driven university student and childhood friend of Sensei. Born to a Buddhist priest but raised by an adoptive family, he defies both households by secretly studying religion instead of medicine. He is deeply principled and occasionally neurotically stubborn. He moves into a boarding house at Sensei's invitation after his academic funding is cut off.

Shizu is Sensei's wife, a woman constrained by the patriarchal expectations of the Meiji period. In Sensei's recollections of their youth, she is known as Ojosan, living with her widowed mother and acting as the focal point of the young male boarders' attention. She desires a closer connection with her husband but continually finds herself blocked by his unexplained emotional walls.

The Narrator's father is a traditional man living in the Japanese countryside, whose physical deterioration mirrors the end of the Meiji era. He places great importance on his son's university graduation. As his illness progresses, he anxiously follows the news of Emperor Meiji's failing health, drawing a direct parallel between the monarch's condition and his own failing kidneys.

The Narrator's mother is a pragmatic rural woman highly focused on her son's professional future and social standing. She actively pushes the Narrator to use his connections with Sensei to secure a job, believing that good news about his career will improve her husband's failing health.

Okusan is a military widow living in Tokyo who rents out rooms in her house to students. She is highly protective of her daughter, Ojosan. She maintains clear social boundaries within her household and carefully manages the interactions between her daughter and the young male students living under her roof.

Sensei's uncle is a businessman who acts as his guardian in the wake of a family tragedy. He manages the family's substantial wealth and initially appears trustworthy, offering Sensei an allowance while he studies in Tokyo. His true motivations gradually come into question as he leverages his position to orchestrate a family marriage.

Emperor Meiji is the reigning monarch of Japan whose failing health and eventual death mark the end of an era of rapid modernization. Though he does not directly interact with the core characters, his illness heavily impacts the national mood and deeply affects the older generation.

General Nogi is a prominent military figure who carries heavy guilt from perceived failures during the Russo-Japanese War. He acts as a powerful symbol of traditional Japanese values and honor. His intense loyalty and adherence to duty resonate strongly with Sensei.

The Narrator's older brother lives away from the family home but returns when their father's condition worsens. His arrival leads to necessary but distant conversations with the Narrator regarding family inheritance and practical matters following a parent's passing.

The Narrator's older sister lives away from the parents' countryside home. She is called back by the Narrator when their father's health takes a significant downturn.

Sensei's aunt is part of the rural household that takes over his family's estate following his parents' deaths. She actively participates in the uncomfortable pressure placed upon the young Sensei to secure his future through an arranged marriage.

Sensei's cousin is the daughter of his uncle and aunt. Though she and Sensei were once very close, she is used by her parents as a pawn in an attempt to secure Sensei's inheritance through an arranged marriage, an offer he firmly declines.