As the attrition rate from fighting the 'Genjuu' beasts is so high, teenaged students are now being called up to fight in HWTs (generic mobile suits). Shibamura Mai volunteers to join the armed forces as a pilot. People live their lives as best they can, when 'Genjuu' beasts appear out of nowhere and attack. When the bell rings, the students jump into their HWTs, go into combat, and oftentimes, die in the process. A series with a great deal of interpersonal relationships involved based on a Playstation game by SCE.