High schooler Natsuo is hopelessly in love with his cheerful and popular teacher, Hina. However, one day at a mixer, he meets a moody girl by the name of Rui and ends up sleeping with her. Soon after, his father announces that he's getting remarried to a woman with two daughters of her own. And who shows up in tow, other than both Hina and Rui?! Natsuo's outrageous new life starts now!
Natsuo and Hina are finally joined together in love. However, their relationship must never be made known. While Hina broods over their taboo love, Natsuo anxiously seeks to take things to the next level, and alas, a gap in their feelings begins to form. Then suddenly one day, a fax outing a “lewd teacher” is sent to the school! As the culture festival approaches, conflict shakes the school…