Isaac of Era

A meek young man with the appearance of a child. He is a skilled jeweler and appraiser that has romantic affections for Taiga, who considers him to be more of a little brother than anything. While he has no problem answering what any gem is worth, he often wonders what he as a person is worth.
Scenes
Catherine buys fake jewelry from Yuu... Decision to tell the truth
Confronting Yuu about the nature of value, objective vs subjective
Taiga's poor craftsmanship
Runs off and disappears for some time, later found in wilderness, "what am I worth?"