In the comedic spin-off manga Daiya no C!!, the members of the Seidou High School baseball team find themselves facing an unexpected challenge far removed from the diamond. Sawamura Eijun and his roommates in dormitory room 5 accidentally adopt a stray cat. The problem is that pets are strictly forbidden in the school dorms. The story follows the boys as they secretly care for their new feline friend, dealing with everyday dilemmas such as how to feed it, where to bathe it, and how to keep its presence hidden from the faculty and dorm supervisors. The series lightheartedly explores the contrast between the intense, disciplined world of elite high school baseball and the chaotic, heartwarming antics that arise from hiding a cat. Key characters include the energetic pitcher Sawamura, his roommate and fellow pitcher Furuya Satoru, the sharp catcher Miyuki Kazuya, and second baseman Kominato Haruichi, along with other teammates who become involved in the secret. The setting remains Seidou High School, with familiar dormitory and practice field locations serving as the backdrop for the comedy. The narrative arcs are episodic, revolving around the team’s attempts to manage the cat’s needs while maintaining their rigorous baseball schedule and avoiding detection. The series is a warm, humorous slice-of-life that offers a relaxed look at the characters away from the pressures of tournaments and ace competitions.