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 finally become one during the school trip. Both elated and anxious to become a man fit for Hina, Natsuo visits Kiriya with newfound determination, and little by little, their love takes steps toward the future. However, thanks to a single photo taken during the trip, the school finds out about their relationship?! What becomes of their unforgivable love…?