At Engetsuza Shrine, there is a magical tale that has been passed down from generation to generation about what happens when a male descendant falls in love. The priest's son, Kounosuke, is an ordinary high school student. Every day he takes care of his childhood friend, Shu, a quiet, laid-back guy. When suddenly one morning, Kounosuke realizes that he is in love with Shu.... and a strange change begins to occur in his body.