Maou ga Calling!

When the dashing demon king invades our human world... The only hero is a fujoshi...

Who would ever believe it's nerdy girl Sanae that will send the lord of darkness back to his realm? Somehow Sanae has to save the world and banish the demon king to Hell. She will harness the power of her virginity, face off against evil so handsome it will make you weep, and achieve heroism!

Oh and there's loads of ecchi. Enjoy!

[From DLsite English]