Hanahaki (Miyusawa)

Sawamura Eijun, a first year pitcher at Seido High School, has developed feelings for Miyuki Kazuya, a second year catcher, and catches the hanahaki disease, a disease caused by unrequited love that makes flowers bloom in people's lungs until they eventually clog their airway and they suffocate. There's two ways someone can be cured, either the person they love gains feelings for them too, or they get a surgery to remove the flowers along with all feelings they had for the other person. In fear of Miyuki finding out he has the disease, Sawamura gets the surgery at the beginning of his second year, after hiding it throughout his first, but what he didn't know, was that Miyuki had caught feelings for him, too.