http://en.wikipedia.org/wiki/Cloud_(game)

The story focuses on 7 year old Jun who has asthma. Because of his disease, he cannot leave his ward without a doctor's permission and often becomes bored in his room. Jun forgets, "feeling of flying headlong through clouds." Fei (meaning fly in Chinese) is a 6 year old girl who Jun befriends in his ward. Fei asks Jun to close his eyes and tell her what he sees, Jun sees the expansive outreach of a cloudy horizon and the game begins.