Chiyuki Matsuoka

The heroine of the story, Chiyuki is a 17-year-old high schooler who is hospitalized due to having a poor heart condition since birth. She has frequent heart attacks when she becomes distressed, and lately the heart attacks have been worsening. She tends to be a spunky person who is able to withstand anything. However, she also can be very emotional and cries a lot accordingly.