Explosive Mechanic Umika, Yu, and Haruno continue developing more sophisticated bottle rockets that achieve greater distances. However, Umika is aware they are nearing the limit of what bottle rockets can achieve, so they need somebody with mechanical experience to help them develop a more complex rocket. They decide to recruit Matataki Raimon, a student with mechanical skills. However, she has not attended class since the first day of school, so the trio head to her house to meet her. They ask her to help build a rocket, but Umika is too shy to explain her reasons so Matataki refuses to aid them...