Takamiya Teppei is a young man who reunites with his brother, Takamiya Kotaro, an important scientist in robotics engineering, to protect him. In the middle of a great conference, Kotaro is taken prisoner by the Machines Empire. While trying to rescue him, Teppei accidentally wakes up a B't (Pronounced Beat) -a combat robot used as a flying vehicle in the shape of a legendary beast- with the name of X. Now, they join forces in order to fight against the evil Machines Empire, which tries to take over the world. (Source: ANN)