The king of debris

"Just as the android and his friends are about to set out on their journey, two deadly Puppetians attack them at once. Corona, Citro's human sister, gets caught in the crossfire, which sends Citro into a rage. His thirst for revenge is fueled by his strength increasing with every fight he wins. When Corona is later taken hostage, Citro vows to completely focus on becoming even stronger. But his judgment seems to be out of control and anyone could be his next victim."--p.[4] of cover.