Kemeko DX

A high-school student named Sanpeita had a dream ten years ago about being engaged to a beautiful girl. One day, a plain-looking girl named Kemeko unexpectedly demands marriage from him. To avoid her, Sanpeita goes to school, but Kemeko follows him and causes a scene. Later, on the school rooftop, Sanpeita and his childhood friend Izumi are attacked by a rice cooker. Kemeko arrives and saves them. The question remains: what is Kemeko's true form?