Aizawa Yuuichi returns to his hometown after seven years, a snow-covered city in northern Japan. He moves in with his aunt, Minase Akiko, and his cousin, Minase Nayuki. However, Yuuichi's return to his old stomping grounds is not carefree, as the boy remembers almost nothing from his previous visits.
Naoe Riki is a quiet and sensitive high school student suffering from narcolepsy and experiencing trauma after the loss of his parents. At the most difficult moment of his life, Riki was pulled out of despair by four peers: the charismatic Natsume Kyousuke, his shy sister Natsume Rin, the muscle-head Inohara Masato, and the kendo master Miyazawa Kengo. Together, they form a tight-knit group that has become a substitute for a family for Riki.