To solve the country's low birthrate problem, the Japanese government set up Otona Kōkō (Adult High School). Adults over 30 with no sexual experience are forcibly enrolled into Otona Kōkō by the government. Eito Arakawa is a 30-year-old single man. He graduated from a prestigious university and works at a bank. He has received recognition for his work there. He is also physically attractive, but he has never had sex. One day, he receives an entrance guide to Otona Kōkō.

One day, Taichi, an ordinary university student, meets Mioka, a girl who is like a storm. Taichi finds himself drawn to Mioka, who lives freely as she wishes without holding back, and they eventually fall in love. However, Mioka tells Taichi of her shocking truth. She has an incurable brain disease, with no medicine or treatment that can help her.

The story revolves around a young woman named Mei, who was rescued as a young girl by someone calling himself her "butler." With only a vague memory, though, the experience seems like just a dream. But one day, after her parents' accidental death, he appears: Rihito comes from a line of outstanding butlers, and he has been appointed to serve her! Now her ordinary life has completely flipped, as she discovers that she's actually the heiress to a fortune, and is forced to transfer to St. Lucia Girls' Academy, where all the students have butlers! As a result, her childhood friend Kento decides to enroll in a butler school so that he can stay close to her.

Nao Kanzaki, a student, was blackmailed into joining a "Liar Game" and ended up losing 100 million yen. In order to repay the debt, she enlists the help of Shin'ichi Akiyama, a genius swindler who was only recently released from jail for bankrupting one of Japan's largest scam companies.