The high school student Oreki Houtaro’s high school life is gray and colorless. One day his life suddenly turns into color because he met A person named Chitanda, she is full of curiosity about everything. Taro originally had a motto, that is energy saving. Because of a very small reason, I entered a small society, the Classical Literature Department. This club is on the verge of being discontinued due to the inactivity of its members and the lack of support from the school. People in the Classics Department, including him, met a curious baby, the heroine Chitanda. There are also Mayaka Ibara and Satoshi Fukube whom he has known since junior high school. The four of them formed a reasoning group and became very good friends. They used high school as the stage to encounter one after another miraculous events, in which they used their rich imagination to reason. The results of these last things also confirmed their ideas. This is a successful youth campus reasoning drama