Yuji Kobari

Also better known as Master, as everyone else call him. The proprietor of "Harry's," a cafe that Robin and other members of STN-J visit often and even worked in during one of the missions. Master also provides the team with information, such as information about witch called One eye. He has a son too, who was seen in one of the episodes, his son is a witch. He is voiced by Hirotaka Nagai in Japanese and Jerry Gelb in English.

(Source: Witch Hunter Robin Wikia)