Shy Chise and nervous Shuji are high school seniors in a small town and have just started dating. But everything changes when Shuji discovers that Chise has been engineered by the Japanese Self Defense Force to transform into the Ultimate Weapon! Soon Chise is torn between realizing her potential as a devastating fighting force and her desire to share a bowl of ramen with her new boyfriend!

Chise is a cute, slightly clumsy, shy teenager--just like most high school girls. But one thing makes her very different--she's been engineered to be the ultimate fighting weapon for Japan's Special-Defense Forces.

To further complicate her life, Chise accidentally hurts an innocent bystander on one of her covert missions. Her boyfriend, Shuji, rushes to help the injured girl and discovers that it's his first love.