Ritsuko Matsunaga, nicknamed Ricchan, serves as a Torpedowoman operating Torpedo Tube 1 aboard the destroyer Harekaze. She belongs to the Weapons Department's Torpedo Committee within the Surface Combat Department, specializing in torpedo operations. Born in Agatsuma District, Gunma Prefecture, she stands 156 cm tall with long dark red hair and wears the standard uniform of Yokosuka Girls' Marine High School. A Libra with blood type B, her birthday is October 12. Gentle in demeanor, she enjoys bowling with notable skill and academically favors mathematics over world history. She strongly prefers butter to margarine and lives by the motto "You only live once." Her given name "Ritsuko" combines characters for "reason/logic," "capital," and "child," while her surname "Matsunaga" signifies "pine tree" and "eternal."