Zero no Tsukaima Season 3

Steamy days and nights of sexual experimentation result from a glance among strangers passing in the street. A young man, enslaved by his own obsessive erotic wants, is magnetically attracted to an innocent-looking schoolgirl he observes outside of his home. Unable to control himself, he throws some of his most private bodily fluid on her, a liquid sign of his sexual desire. Surprisingly, she responds favourably to this bizarre come-on, and the two end up living in their own illicit world for the next several days.
(Source: yahoo movies)