Set in the early 20th century, Kokoro opens with a chance encounter on a beach near Tokyo that irrevocably links a young student to a man he simply calls Sensei ("Teacher"). Intrigued by Sensei's aloofness, the student calls upon him with increasing frequency. Eventually, Sensei and his beautiful wife open their home and their lives to him. Only later does the student learn the devastating secret that has haunted Sensei since his youth. Kokoro has sold millions of copies in Japan where it is taught in schools and is a perennial favorite. Its lucid prose and universal themes of friendship, betrayal and the struggle for meaning in a changing world have made it popular internationally as well. The manga includes depictions of suicide and may not be suitable for some readers.