Yuna has such bad luck in life that she is told she won't live to be 25 and that she is lucky to be alive. Unlike other people, Yuna thinks she is normal except for the "black fog" she sees, but an "event" that she herself has forgotten has had a major impact on her destiny. When Yuna turns 22, she is depressed because her job search is not going well, when a mysterious beautiful boy appears and saves her from a crisis. He is kind and friendly to Yuna, and his true identity is...?