Happiness! centers around Yūma Kohinata, a high school student attending Mizuhosaka Academy's regular section of the school, and his close friends Jun Watarase and Hachisuke Takamizo. The other section of the school, aptly named the magic section, was founded in order to train mages in the art of using magic. The day after Valentine's Day, a gas explosion at the magic section causes all the mages in training to transfer to the normal section for the time being. Two girls from the magic section, Haruhi Kamisaka and Anri Hiiragi, are placed in Yūma's class. Now Haruhi and her friends must adjust to the transfer into the normal section of Mizuhosaka Academy.