"Kokoro (Heart)" is a novel written by the Japanese author Natsume Sōseki, first published in 1914. The story explores themes of loneliness, friendship, and the complexities of human emotions through the relationship between a young man and his mentor, referred to as Sensei. The narrative delves into the psychological struggles of the characters, reflecting the societal changes in Japan during the Meiji era. The title "Kokoro" translates to "heart" in English, symbolizing the emotional core of the story. The novel is divided into three parts, each revealing deeper insights into Sensei's past and his feelings of guilt and isolation. It is considered a classic of Japanese literature and continues to resonate with readers today.