Lillian Night: Exclusive Contract of Succubus

As I lay in bed, ready to start my nightly routine, a girl appeared out of nowhere, right in front of me! I said "girl", but she had wings and horns - not to mention she could fly! I'm pretty sure she's not human... I mean, she drank a load of my cum, calling it a taste test! Apparently, she liked it enough to offer for us to form a "contract". Uhh... I'm not entirely sure what I'm supposed to do here...

[Edited from Steam]