世良 花蓮

A third-year student of Suzuo Academy Senior High School. Karen is a shy and fragile boy with a weak body. Due to his weak constitution that lead him to being absent from school often, plus his shy nature, he's often on his own. He's good at listening to others but not talking about himself. When Karen is healthy, he enjoys his only hobby- taking pictures while going on a walk.

Haruho met Karen when she was a sixth-grade primary school student. Around that time, Haruho became ill and collapsed, which required her to get hospitalised. When she felt better, she wandered around the hospital courtyard and met Karen. They became friends and swapped books with each other.