The high school student Kobayashi Sanpeita dreams he is engaged to a beautiful girl. Then one morning, a strange homely girl suddenly breaks through a wall in his bedroom, fighting spider-like battle droids, to tell him that she is his bride and that her name is Kemeko. In order to escape, Sanpeita flees his home and runs to school, but Kemeko follows him.

And things only get stranger when Sanpeita is targeted by something that looks like a rice cooker on the school's rooftop. As Sanpeita and his childhood friend Makihara Izumi are being attacked, strange little Kemeko intervenes to save them both. But just who is Kemeko? Someone who claims to be Sanpeita's new steel bride!?

Sanpeita is surprised to learn that Kemeko is actually a girl-style powered-combat-suit and that the pilot is a cute girl named Mishima Mei. She may be a heavily armed and violent girl, but still quite cute, nonetheless.