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Kokonoe Yakumo (九重 八雲) is a famous ninjutsu-user and someone who passes on traditional shinobi magic. Kokonoe is the master of Shiba Tatsuya.
Appearance and Personality
Despite his massive physical and magical talent, Yakumo has a childish personality with an inclination to play childish pranks. He constantly hides his presence and sneaks up on people to scare them. Just looking at him gives a sense of a lack of propriety. He likes darkening rooms and spooking people that come in. He has an "altered" sense of social boundaries, somewhat like Tatsuya, readily admitting to gathering intelligence about people. He also likes teasing people, which some don't really take well.
He is a friendly guy who helps out upon request, although this might be only for Tatsuya, as he was once called Yakumo's favorite disciple by Ono Haruka. However, Yakumo has also given Haruka high praise for her abilities, according to Fujibayashi Kyouko. But even that has its boundaries, as shown when he wouldn't teach Tatsuya, officially, a way to counter Ghost Walker, because he wasn't a student of him at that moment.
Yakumo is shaven bald and does not give the impression of age. He usually wears a monk's robe, despite it not really fitting him and his personality.
He is likely to be in his 30's as he once said that Tatsuya is only half of his age. 
A self ascribed shinobi, Yakumo is a wannabe monk, according to 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" also known as "Warrior Monks". Yakumo is 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 Tatsuya, Haruka, and Kazama Harunobu. Shiba Miyuki has also undergone some training from Kokonoe Yakumo. As a practitioner of Ancient Magic, he shares a close relationship with the Fujibayashi family, which is also a family of ancient magic users. Second Lieutenant Fujibayashi knows him personally and may have even received training from him.
As a master of ninjutsu, Yakumo has amazing physical capabilities, as well as knowing all the illusion and body enhancing magic that ninjutsu has to offer. He can hide his presence to an amazing degree and is also capable of seeing pushions. He is trained in a multitude of weapons, including kunai, marbles, and expertise in hand-to-hand combat.
His information network is truly astounding and he uses it without restriction. He looked into the "eyes" of Shibata Mizuki and had gathered information about Blanche's objectives when they threatened First High School. Having disciples like Haruka in Public Safety, Tatsuya and Miyuki in the Ten Master Clans, and Kazama in the National Defense Force 101 Independent Magic-Equipped Battalion is definitely a bonus to him.
Due to his ability to see the aura of both Tatsuya and Miyuki, it can be surmised that he has Over Sensitivity to Pushion Particle Emissions, the same as Mizuki. It can also be surmised that he is just as powerful as Mizuki, as he is able to see Tatsuya's inner aura and comprehend exactly what he is seeing.
- Onibi (鬼火, Will-o'-the-wisp)
- A high-quality illusion spell, which produces ghastly orbs of light, swirling around the user and wherever he points to. The orbs created by the Ninjutsu Magic are more accurate and more mobile than those made by Modern Magic.
- Matoi (enshroud)
- Focuses on creating a body clone of the user and is the original and ancient version of Parade.
As a ninjutsu master, Yakumo is capable of fighting with a multitude of weapons in both ranged and close combat. In close combat, he has used bare hands and swords even if it was wooden. In ranged combat, he has used kunai, although weapons like marbles are probably also used by him. Seeing as Tatsuya is his disciple, he may also use his physical capabilities to get into a person's blind spot and attack from there, either hiding his presence and/or using magic to boost his speed. True to the spirit of a ninja, Yakumo will utilize anything in his environment to his advantage, allowing him to defeat even Tatsuya consecutively without Trident or his innate magic, despite admitting he may not be able to defeat the latter in 'pure martial arts'. In terms of strategy, he vastly outstrips Tatsuya.