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?