Kannagi

Kannagis are first mentioned when Tsuchigomori refers to Yashiro as such in chapter 13. In this chapter, Hanako claimed that being a kannagi meant being his assisant. However, we later find out that Kannagis are young women in the old town Akane Sumire lived in (and on top of which Kamone Gakuen was built) that were choosen to be sacrificed in order to appease the supernaturals.

It is believed that when a young girl is sacrificed, the world of humans and supernaturals will separated, which means humans won't be attacked and killed by supernaturals. This seems to only work for a short while, as the town must keep sacrificing more girls every once in a while. In modern day, supernaturals are rampant in Kamone Gakuen Academy, since no kannagis have been sacrificed for a long time. Aoi's sacrifice caused the severance, however it was undone when she was brought back to the nearshore.

Kannagis are said to often come from the Akane family, but are not exclusive to them.

In real life, the term kannagi refers to a shaman or a miko from Shinto. These people work in shrines, gaining a small salary but are very respected in the community. They help with ceremonies and perform traditional dances, and also sometimes fulfill other needed responsibilities.

Appearance
When kannagis are to be sacrificed, they're dressed up in Miko clothing, which consist of a white kosode and a hibakama. They do, however, differ from real life miko clothes in a few ways. Their hibakamas are a long skirt, instead of hakama pants, with a slit in the middle, revealing a frilly underdress. They also have string to decorate their sleeves, and a large ribbon tied on their lower back. Unlike real miko clothing, these outfits seem to come in different colors, Nene's being the traditional white and red, yet Aoi's is light blue and dark brown. Both Nene and Aoi also were given two roses to their hair to complete the look.

Named Kannagis

 * Akane Sumire
 * Katakuri
 * Yashiro Nene
 * Akane Aoi

Trivia

 * Yashiro Nene is the only kannagi who is not from the Akane family.
 * It's been implied that Yashiro's ability to rip off yorishiros is due to her being a kannagi, but she's the only kannagi we've seen do this.
 * Katakuri is the only known male Kannagi, which is because the town was running low on young girls at the time.