Окумура Юкіо

Yukio is Rin Okumura's twin and younger brother and Shiro Fujimoto's adopted son. He is a Middle First Class Exorcist who has started his training to become an Exorcist at seven by his father suggestion and, since then, gained the titles of Dragoon and Doctor at only fourteen, becoming the youngest Exorcist in the True Cross Order history. Yukio is also the youngest teacher of the True Cross' Exorcist Cram School, at which he teaches pharmacology. Before he was born, he has had a weak body that couldn't bear the power of the blue flames, causing the power of Satan to be fully inherited by Rin.

He is seen as an ​example and prodigy by the ones who live together with him and is friends with Shiemi Moriyama, who calls him Yuki-chan.