Saint Valentine Wars

Due to her parents' work, Serina Aoyama is staying with her father's best friend, Dr. Yamada, a doctor of engineering. Her son, Susumu, is strong despite his cute face. After all, he's a cyborg! (Source: Manga Library Z, translated) *Note: Includes the one shot Saint Valentine Wars (セントバレンタイン☆ウォーズ).*