Kouichi Mizuki, a popular and athletic high school student, faces uncertainty about his future as he navigates his relationships with his basketball club members and classmates. One day, he mysteriously disappears from his room and finds himself in a strange place, confronted by the titan prince, Caius Lao Bistail, who claims Kouichi is meant to be his bride. Despite Kouichi's desire to return home, Caius asks for a month to win his heart. This unexpected love story challenges the boundaries of size and species, posing the question of whether their connection can transcend such differences.