Takayukashiki Shoujo

Kamiwazumi Jun lives alone in an old house with a shrine. As a result, people sometimes leave random things outside his house, like kittens... or an unconscious naked girl?! The woman in question claims to be a robot from the future who has come back in time to protect Jun, the future messiah. She has no qualms about nudity, and retrieves useful objects from a "9th dimensional pocket" between her legs. Once Jun has accepted that her story must be true, he also has to figure out how to work a sexy robot girl into his everyday life, which also includes explaining her to a cute childhood friend that has a crush on him.

(Source: MangaHelpers)