Freshman Xu Sangsang meets the best roommate Wang Xiangqin and the cute and fat girl Wang Junyi. Her college life begins with a daily surprise and frightening experience like a bloody idol drama. Li Yingyi, a handsome man who has a crush on Wang Junyi, and Hu Jiejie, a gay man, both have their own unknown secrets, while the friendly freshman training officer Harmless Platoon Leader is actually a smiling tiger hidden in the darkness, and there is also a shocking shady plot manipulated by Yang Ke, the president of the student union... Just as Xu Sangsang was worrying about her increasingly bizarre college life, a mysterious new roommate arrived, and her life was simply beyond the imagination of normal people. "Four Swings on the Third Floor" tells the story of college life with some rules, reveals the life of college students under the intellectuals, and laughs at all the disharmony among the so-called righteousness on campus. Is a university an ivory tower? Or is it the experiential society of the harsh world?