When Fuyuki Hino walks into the wrong locker room, he makes a startling discovery: one of his classmates, Yomina Sakuba, is undressing—and has wings! Caught off guard, Yomina reveals that she is a half succubus. Fuyuki agrees to keep what he saw a secret but is nonetheless dragged into her strange situation.

After the locker room incident, the two befriend each other. Despite her aloof appearance, Yomina yearns to socialize with others. After Fuyuki learns of her true personality, he joins her venture to develop new friendships, navigate comical situations, and enjoy their time together as regular high school students. However, Yomina's half-demon identity still presents them with a variety of challenges.