Park Sunghoon or usually called Sunghoon is a 17 year old boy who has had heart disease since childhood. He is handsome and wise. Since childhood, Sunghoon has only studied from home via homeschooling. But Sunghoon usually left the house as long as he wasn't alone. His parents didn't let him go out alone and according to Sunghoon they overdid it. Sunghoon dreams of being cured of his illness, but he thinks it's impossible so he always secretly throws away his medicine.