Moburi-san is a high school girl who takes on an older sister role for two boys dedicated to uncovering local mysteries and treasures. Her journey intertwines with theirs through a quest to locate seven hidden gems tied to a legendary flying castle, drawing them into clashes and alliances with rival treasure hunters. As they navigate these challenges, she emerges as a pivotal figure in steering the group through obstacles, their collective decisions carrying weight over their city’s fate. Her interactions underscore her seamless integration into the team’s core dynamic, where collaboration and resourcefulness drive their shared mission. The narrative anchors her contributions to collective problem-solving within the framework of their documented adventures, emphasizing teamwork over individual exploration.