
Soseki also feels that Sensei has erected a wall between them and one day confronts Sensei with his suspicions. Shizu loves her husband, but Sensei hides what torments him and has spent their wedded life just outside of her emotional reach. Shizu explains to Soseki that a friend's unnatural death coincided with the slow descent Sensei has taken into isolation. Soseki learns more about Sensei through his wife, Shizu and his knowledge and feelings for her grow as well.

Often Soseki is confused and disappointed by Sensei's words and believes the older man's perceptions of him incorrect. Sensei believes Soseki has sought him out because he is lonely, but himself unworthy of society and unable to help the younger man.

Soseki is a young man bored with life when he befriends Sensei. Kokoro is a tale that gets to the heart of the loneliness, fear, and guilt that accompanies love, individuality, and betrayal. Only when Sensei decides to end his life does he decide it is time to pass on his testament. Though Soseki and Sensei develop a close friendship, Sensei's life remains a mystery. What Soseki does learn is that Sensei is a troubled and reclusive man who does not trust himself or humanity enough to interact with the world. Soseki befriends an older man he calls "Sensei" with the expectation of learning about life. It is the story of many individuals who long to appease loneliness, and the story of two men who attempt to assuage loneliness through love but only find peace in death.

