The story takes place in the city of Meinan in northern Kanto, Japan. The four unreliable high school boys, Shuzenji Kagami Taro (voiced by Shimotsuru Naoyuki), who has no energy and does not look like a young man at all, Kirishima Ryoma (voiced by Ishii Takahide), who looks very energetic but unexpectedly has no willpower, Manza Prince (voiced by Yasuda Rikuya), who has a super rich brain knowledge base, and Dogo Ichiroku (voiced by Hayama Shota), who will go all out no matter what he does, form the "Earth Defense Department". Although the name sounds very powerful, in fact, everyone does nothing every time they work, and they are very leisurely and lazy. One day, in an accident, a beautiful boy from another world named Calulus (voiced by Eguchi Takuya) came to the Earth Defense Department by mistake.