Complex sentence: He pilots the Pezun Asteroid's MS-11 Act Zaku, often displaying an implacable absolute confidence in his abilities, he becomes obsessed with destroying the Thoroughbred and develops a rivalry with the RX-78-4 and its pilot, Lusse Kessel.
Split into simpler sentences: He pilots the Pezun Asteroid's MS-11 Act Zaku, He has an implacable absolute confidence in his abilities. He becomes obsessed with destroying the Thoroughbred and develops a rivalry with the RX-78-4 and its pilot, Lusse Kessel.