Episode 6 of "Bullbuster" begins with the introduction of Shuichi Namari, an intern from Shiota Chemical, who is working at Namidome Industries for a month. His arrival comes at the right time, as Ginnosuke Muto is still recovering from his injury, and Namari's boat license is particularly useful for the company's work.

Tetsuro Okino is tasked with briefing Namari on everything, including the Bullbuster robot and the boat used for transportation to Ryugan Island. However, Namari quickly criticizes the design and efficiency of the Bullbuster, pointing out what he believes to be inadequate energy capacities.

The story continues with the ongoing threat of the giant beast. Another sighting leads to an immediate mission, but Namari refuses to participate, citing company rules that prohibit overtime during his internship. His adherence to the rules despite the potential danger posed by the giant beast creates a rift between him and the rest of the team.

Meanwhile, Arumi Nikaido participates in an experiment with a GPS-equipped mouse to track the mutation process of the giant beast. The experiment takes a turn when the mouse returns to the mainland and is pursued by a giant beast.

As the team prepares to confront the beast, Namari's refusal to help due to his strict interpretation of the rules leads to a heated confrontation with Okino. Okino accuses Namari of lacking empathy and being a problematic employee at Shiota Chemical, which Namari denies by defending his actions as compliant with the rules.

The episode also delves into the personal struggles of the characters, including Arumi's emotional moment with her mutated dog Shiro and the team's financial difficulties in acquiring a new aquatic robot for their missions.

The episode ends with the successful elimination of the giant beast, but the tensions within the team and the challenges they face are far from resolved.