Miko is the heroine of all La Blue Girl OVAs and a kunoichi. She is the last descendant of the female Miroku ninja clan, which has been feuding with the Suzuka clan for many generations. She is often very annoyed at being a sex ninja and having to use her body as a weapon against opponents. Miko can use many unusual sexual techniques, such as hardening her pubic hair into needles and firing them at an opponent, or the 'Nyoninboh' technique which allows her to swell her clitoris to the size of a man's penis and drive female rivals crazy with it. If strands of her hair are torn out, she can use them as acupuncture needles to stimulate her opponent's erotic pleasure points. Her most powerful attack is the 'Aoi Tatsumaki' (Blue Whirlwind), in which her hair turns into a giant blue tornado that invariably rips away all of her clothing.
Miko is the daughter of Seikima, the King of the Shikima, and of Maria, the Queen, who is human and a former Miroku woman. As such, Miko is a demon-half-breed and has the blue coloured blood of the Shikima, hence the title 'La Blue Girl'.