Gauvain is the father of the protagonists Shion and Marie, serving as the head of the lower-ranking noble Ornstein family. As the family patriarch, he assumes significant responsibilities within his domain, carrying the weight of leadership for his household. The villagers place deep trust in him, and his presence fosters a sense of security throughout the village.

Gauvain is described as a highly skilled swordsman, with his excellent swordsmanship being a notable aspect of his abilities. His proficiency with the blade, combined with his high integrity, earns him respect from many people within the community. No information is available regarding his background prior to becoming head of the Ornstein family, his personal motivations or goals, his specific role in the story's plot progression, his relationships beyond being father to Shion and Marie, any character development he undergoes, or any other notable abilities besides his swordsmanship.