A group of high school girls at Momozono Academy discover a shared passion for building and customizing 30 Minutes Sisters model kits, leading them to form an unofficial club. The story centers on the energetic and impulsive Ritsuka Misora, the calm and analytical Sakuya Kiyomizu, and the soft-spoken but prodigiously talented Tina Hoshino, who together navigate the joys and frustrations of snap-building, painting, and posing their plastic figures. Their daily activities take place against the backdrop of modern-day Japan, with key locations including the school’s craft room, a local hobby shop named Model House, and various competition venues. The narrative unfolds through several arcs: the formation of the club and their first regional contest, where a broken part nearly derails their entry; a summer training camp that introduces a rival school led by the stoic designer Kaede Shijou; and a winter cultural festival arc focusing on a collaborative diorama that tests their friendship when creative differences emerge. As they encounter obstacles such as limited budgets, misplaced runners, and the pressure of public judging, the girls learn that true mastery lies not in winning but in the patience, resourcefulness, and mutual support found in the building process itself.