Yakumo Kokonoe

Kokonoe Yakumo is a famous ninjutsu-user and someone who passes on traditional shinobi magic knowhow, Kokonoe is the master of the series's protagonist, Shiba Tatsuya.

A self ascribed shinobi, Kokonoe Yakumo is a wannabe monk, according to Shiba Tatsuya, despite having the qualifications of a monk. He is a master of a form of Ancient Magic, Ninjutsu, and owns a "Temple" with "Practitioners of Austerities" that are also "Warrior Monks." Yakumo is also a former member of the JSDF, a well known master martial artist among fighting circles and is considered by many to be one of THE authorities on Ancient Magic.

People who have trained under him at the dojo as students include Shiba Tatsuya, Ono Haruka and Kazama Harunobu. Shiba Miyuki has also undergone some training from Kokonoe Yakumo. As a practioner of Ancient Magic, he shares a close relationship with the Fujibayashi family, which is also a family of ancient magic users. First Lieutenant Fujibayashi Kyouko knows him personally and may have even received training from him.

(Source: Mahouka Koukou no Rettousei Wikia)