Princess Emerald is the princess of the Emerald Kingdom (hence the name). She first met with Frost when he was sent to the Emerald Kingdom and snuck past the guards, who wouldn't allow him in, in order to send a message to the King to warn the kingdom about an oncoming attack from Holy Nightmare. Frost ran into her while meandering through the castle's halls; she was initially skeptical of him, but came to the decision to help him talk to the king. Once the demon beasts imminently arrived, Frost contacted the Galaxy Soldiers and was ordered to escape. Princess Emerald followed him despite any possible objections he could have made. After those events, she and Frost have grown to become good friends. She eventually made him into an Emerald Knight, several years later.