La☆Blue Girl

The story involves various ninja clans who continually fight each other. The female protagonist is Miko Mido, a young ninja-in-training and the next leader of the Miroku ninja clan. This clan has control over the Shikima, a perverted race of demons. However, when thieves steal the magic compact giving the clan this power, Miko has to fight the Shikima, utilizing her "sexcraft" ninjitsu in order to save the world.

The Shikima live in a parallel dimension called the Shikima world, and one must perform specific sexual rituals in order to travel there. The Shikima are all sex-hungry monsters, led by the Shikima Lord, who also happens to be Miko Mido's father.

(Source: Wikipedia)