In Matsuyama, two young friends named Mattsu and Yamma take great pleasure in unraveling the mysteries surrounding their city's renowned "seven wonders of Matsuyama." During their quest, they encounter two unfamiliar faces who are interested in gaining knowledge about these hidden treasures. Joining them on this exciting journey is Moburi, someone who has been like an elder sister to the boys since high school. Together, they embark on a thrilling adventure that lays the groundwork for a fascinating story set in Matsuyama. In the face of various obstacles, the trio is confronted with a crucial decision that will have a positive impact on the future of their beloved city.