Sougo Amagi

Sougo is an ecstatic boy who likes to collect rare crystals for his hobby, a fascination he inherited from his mother Ena. He wants to prove one of his mother's theories about the existence of a certain red gem called Lucifer. He has a tendency to act recklessly. After finding Felia in a cave, he goes on several adventures with her and his friends Kaon, Roman, and Otto.

(Source: Wikipedia)