what's the word in Japanese?Otome? like it could be translated either as maiden or virgin?
Nope. The word used is 処女 (shojo - virgin), not to be confused with the 少女 (shoujo - girl) that's in the title. Technically it can also mean maiden in certain situations, but virgin (as in "hasn't had sex") is the definition used in this manga.
This seems good from what little I've seen. I'm not sure I'd be so quick to make a contract with a magical being who may or may not be violently jealous, but I'm no manga protagonist so you do you sis.