Happiness! focuses on Yuuma Kohinata, a high school student in the regular section of Mizuhosaka Academy, alongside his close friends Jun Watarase and Hachisuke Takamizo. The other section, appropriately called the magic section, was established to train mages in the art of using magic. The story starts with Valentine's Day approaching in just a few days, creating a rush for all the girls to get the chocolate they want to give to the boys they like, following Japanese custom. Haruhi Kamisaka, a mage in training, is out with her friend Anri Hiiragi, also a mage in training, to do exactly this. While walking outside in the park, after buying the chocolate she intended to give to a boy she met in childhood, Haruhi encounters Yuuma, who stops some younger boys from bullying a young girl. Haruhi thinks that he may be the boy she has been searching for all this time. The next day is Valentine's Day, and at school, all the girls are giving their gifts to the boys of their choice. Later that day, Anri challenges Haruhi to a magic battle to take the chocolate she has by force, because Haruhi wouldn't tell her who she was going to give it to. Before long, Anri loses control of her magic, and it flies outside, almost falling onto Yuuma and his friends. Ultimately, Haruhi gives him the chocolate she had bought, and in turn Anri does the same, which was her plan - to give her chocolate to the same boy as Haruhi and see who would win his favor more. The next day, there is a gas explosion at the magic section of the school, and all the mages in training must transfer to the normal section for the time being. Coincidentally, Haruhi and Anri are placed within Yuuma's class. Now Haruhi and her friends must adjust to the transfer into the normal section of Mizuhosaka Academy.