Ultra Series 1: Rival

The first part of the Ultra series trilogy, "Old Enemy" main CP Saibei. In the early stage, Besai is more obvious, but the theme is based on Saibei. When did the change happen? The arrogant Dark Emperor, can he tell the difference between love and hate? Is it your unwillingness to be ruined by the young boy again and again? Is it the desperate desire to trample that hateful boy underfoot? Is it the urge to hold a vulnerable and helpless child in your arms? Still Want his life? The story has been written long ago, and the protagonist and villain are already destined. "Zero, we are old enemies, eternal enemies."