Taboo Tattoo: Tōko Ichinose

Toko is Seigi childhood friend and classmate.  After being possessed by Iltutmish she accidently gets a tattoo that uses her willpower to give her great strength.

Nyan Koi! : Nagi Ichinose

Nagi is an athletic senior who specializes in track.  She is also the heir of an yakuza family with astaphobia (fear of lightning).  Her boyish looks and tomboy behavior often gets her mistaken for a boy.  In typical harem comedy fashion she develops a crush on the protagonist.