In their childhood, a group of seven friends called themselves the World Defense Force. Led by Hiiro, the group embarked on adventures together. However, when Hiiro had to move away, she entrusted the leadership to Ai, the protagonist. Sadly, not long after, Ai disbanded the club, and the group gradually lost touch.

Years passed, and in high school, Hiiro returned to find that the group no longer existed. Surprised and determined to reunite everyone, Hiiro enlisted the help of Kamome. Together, they established a new school club called the Shrine Defense Club, with a mission to protect the school's peace by listening to students' problems.

As they began to fulfill their new purpose, mysteries started to unfold, piquing the group's curiosity. The club members embarked on investigations to unravel these mysteries, all the while hoping to understand why Ai hesitated to rejoin them.

Along the way, their old members gradually rejoined the club, with the exception of Ai. As they delve deeper into the mysteries, they strive to solve them and uncover the truth behind Ai's reluctance to rejoin their ranks. Will they succeed in solving the mysteries and bringing their group back together once again?