B't X

A robotics prodigy named Kotaro is targeted by a hostile organization seeking to use his skills to advance their Machine Empire and its AI entities called B'ts. When Kotaro is captured, his younger brother Teppei attempts to save him. After an attack by a powerful B't and its pilot, Teppei's spilled blood awakens a legendary B't known as B't X, which bonds with him. Now, Teppei controls one of the most dangerous sentient beings, but the brothers face overwhelming opposition from the Machine Empire's forces. Even if they manage to endure, B't X is reluctant to confront another B't from the Empire.