Isabella, a servant banned from training, tamed an Abyssal Dragon in the successor trial and was accepted by Headmaster Albert. She fell for the Archmaster Caterina, but Caterina was bound by Albert's puppet curse, forced to obey him as his weapon. His plan is to sacrifice them both to break the Abyssal Seal. Caterina tried to push Isabella away to save her, but Isabella refused to leave. When Albert seized control and turned Caterina against her, Caterina killed herself to destroy the ring binding her. In grief, Isabella awakened as the Saint Magus, merged with Caterina's golden magic, purified the darkness, and killed Albert. The academy was rebuilt, and the two women stayed together in peace.
