Hisaya had been living in Tokyo since leaving his hometown of Goshiki-mura when he was in elementary school. Lately in his dreams, he often saw a young girl who seemed to want him to return to the town. So, he headed back to his hometown since he felt that he was more suited to the rural lifestyle. After reuniting with his childhood friend Tamami, enrolling in the local school and settling into a ryokan managed by Tamami’s parents, he was ready to resume his small town life.
There’s a legend that the local onsen grants special powers to people. One day, he saw a naked Tamami in the onsen, her whole body glowing in a strange light. Then a strange cat being convinced him to sign a contract and he was led to broadcasting room at the school. The school principal Mao explained that this was actually the secret club Heptagram gathered. Lately, there have been many mysterious incidents (arch) happening around town and it was up to the Heptagram members to use their anti-arch powers to solve them. Of course, because he found out about Tamami’s secret, he was recruited into Heptagram to assist the girls.