Who is K from Kokoro and what is their importance?

K is a young boy, who was adopted by an affluent doctor. Expected to carry on the medical tradition, K decides to follow his heart and study religion. As a result, he is financially cut off from both his adopted family, as well as his birth family.

K goes onto to work and finance his own education, declining assistance from his mentor, Sensei. In addition to offering financial assistance, Sensei also offers a place to stay. K accepts. Over time, K falls in love with Ojosan. In the end, hopeless, lovelorn, and jealous..... he takes his own life.