In Fujisawa, Sakuta Azusagawa is in his second year of high school. Blissful days with his girlfriend and upperclassman, Mai Sakurajima, are interrupted by the appearance of his first crush, Shoko Makinohara.
One year has passed after the great battle against the Orochi (gigantic snake). Tenka Kumo had been paralyzed from the final battle and he took part of the government’s human experiment before the battle. Tenka withdrew himself from society but his younger brothers Soramaru and Chutaro find out the secret past about their older brother.