Takaomi Matsubue and Arika Togawa are second-year students at the same high school. By some strange quirk of fate, they started dating. Matsubue-kun is a really weird guy (in truth, other people just don't understand him), which causes Togawa-san to ponder: "Why do I like this guy anyway? Why do people fall in love?"

They encounter a baffling mystery: Tsugumi Yoshimoto, a girl who has been sleeping, sleep-eating, and sleep-walking for half a year. According to Touko and Rinko Mishima, sisters who are also well-acquainted with the structure and interpretation of dreams, this is a matter that concerns them all...