In this episode, Umika Konohoshi, the chairperson of the newly founded Rocket Research hobby group, is brimming with excitement for their first official club day. However, the group faces a setback when they learn that their club is only recognized as a hobby group and not as a full-fledged club, meaning they receive no funding and only an empty classroom for their activities.

Despite this disappointment, the group decides to make the best of their situation. Their advisor, Emihara-sensei, provides them with a small sum of money, though it falls short of their ambitious rocket-building plans. Matataki Raimon, known for his expertise in rocket engineering, steps in and suggests using a lighthouse as their workspace. The lighthouse, which has mysteriously regained its power since Yu Akeuchi's arrival, is declared their secret base.

The group begins constructing rocket models. Matataki leads a workshop where he teaches the basics of rocket building and the principles of propulsion. Each member manages to build a model rocket, even if they find the process challenging.

As club president, Umika is encouraged to take on a leadership role, including proposing a toast to their new hobby group. The episode also features a tender moment between Umika and her younger sister, highlighting Umika's growth and newfound responsibility.

The episode culminates in a model rocket event, where the group visits various rocket exhibitions and participates in activities with Emihara-sensei. They meet Kei Akizuki, a second-year student at Tatsuoka High School of Science and Technology and the chairperson of the Space R&D Club. Kei, who had previously helped Umika and her friends, proves to be a skilled rocket builder and impresses everyone with the successful launch of a jumbo model rocket.

The episode ends with the group, inspired by the event and Kei's leadership, deciding to participate in the upcoming model rocket championship.