In the mountain town of Rinin City, the student president at the sole high school leads a double life, balancing official duties with oversight of a hidden society. Episode one introduces the ancient ceremony passed down through generations, enacted between the new moon and full moon to shield the region from illness and poor harvests by honoring its guardian deity. Through the president’s perspective, the story reveals how select participants tied by family bonds carry out the rite in secrecy. The episode establishes the ongoing legacy of these customs within the school’s private circles.