Retto and others head to a nest of Kiseichuus to rescue Kirara who was abducted during a battle. Meanwhile, Kirara sets herself free from an enemy restraint and wanders alone in the nest. She comes across Chacha, a princess of Kiseichuus, who is considered different from the others due to her mutation and has been imprisoned. Chacha wants to stop her other comrades from destroying humanity and plans an escape with Kirara. Retto and others finally arrive at the nest and charge head-on, but…

The HxEROS headquarters generously grant Retto and the team a vacation at the beach, but when they arrive, they discover that the beach is covered with suspicious-looking sea cucumbers. Discouraged at the prospect of not being able to go swimming, the team head back to the hotel where they run into the Tokyo Branch, who have arrived to exterminate the sea cucumbers, and end up helping them in the extermination. Toma Taiga, the only male member of the Tokyo Branch, asks Retto to be his mentor. Toma says he admires Retto, but what secret is he hiding?