Ritsuko Inoue

A 16-year-old high school girl and military otaku. She's a tomboy but not to the point where she loses her femininity. Drives the tank and also acts as a sniper from time to time; she often sets landmines and booby traps. Despite her love of modern military hardware, Ritsuko also displays a more sensitive and innocent side: she falls in love with the cute Pichi and maintained a belief in Father Christmas long after her peers had abandoned it and is also frightened to death of ghosts. Ritsuko carries a Heckler & Koch USP40, G36C Assault Rifle, PSG1 Sniper Rifle, a sheath knife and some C4. Her I.Q is 500. She also speaks fluently in English and German (source: Wikipedia)

In the manga, she demonstrates a clear affection to Junpei and is shown to be extremely jealous when Junpei is approached by another girl romantically.