Yllbora is a reserved but ambitious general who can be egotistic and aggressive, but noble and courageous. He is 20 years old, and is known as "The Best Warrior of Ladorio". He tends to look down on others, but seems to be deeply in love with Romina, and is determined to fight for her to the end.

He becomes very jealous of Romina's attention towards Joe. Both he and Joe are "people of action" and this mutual antipathy ends up in open quarrels and fights, which tends to upset the otherwise peace-seeking Romina. He dreams of great power; when Zaboom general Grathan Gryn offers him power in exchange for princess Romina's life, he considers the offer and leaves the Xenos 5 for good. However, he cannot forget his love for Romina, and is racked with guilt.

Yllbora eventually pilots a ninja robot named Zerokage. He remains conflicted between absolute power and loving Romina. At the end of the story, when he becomes seriously injured, he decides to tell Romina his feelings.