Yohko Mano seems like a normal 16 year old, dreaming of boys and just hanging out with her best friend Chi. But things were soon to change. One day while swimming in a public pool, Yohko is attacked by a demon. While she is struggling to escape, a burst of power comes out from within her, freeing her of the beast. Later that day, she discovers from her grandmother that she comes from a long line of mamono, or devil hunters. Yohko learns that many of the female members of the Mano family have been mamono hunters, defending mankind and fighting demons throughout history.

Yohko transforms into a red silk dress clad mamono hunter by using a Yoma ring given to her by her grandmother. Worn on her left hand, this ring is the source of Yohko's power. It has healing properties and has the power to control time. The ring itself can also help Yohko generate a power blast to use against her enemies. However, Yohko's main weapon is her Soulsword which she calls to her as soon as she transforms. This sword's long blade can be detached from the handle. And if the need be, Yohko can call the sword back to her.

However, Yohko's life isn't easy... did you think it was? She has to put up with Azusa, an over-enthusiastic Devil Hunter in training. And let's not forget her cousin, Ayako, who happens to look exactly like Yohko (except she wears a black silk dress). Ayako has a major vendetta against Yohko because all of her life, she's been taught that SHE was meant to be the 108th Generation Devil Hunter. Sometimes the problems overshadow the perks. Especially when it's SO hard for Yohko to get a boyfriend - with any boys she ever liked turning out to be either possessed by demons, sacrificed for evil, or were illusions to begin with! Not to mention the fact that Yohko must retain her... honour... until she has earned her title as the 108th Generation Devil Hunter.