Blood Midnight Blossom

The main character is an ordinary girl named Annihilation, who lives in a small town A. She inherits a huge debt from her father and is desperate to find a way out. On the street, she meets a stranger in a raincoat, called Catharsis, who offers a demonic part-time job for a week.

Catharsis is a vampire who lives in a world hidden from the eyes of ordinary people. For hundreds of years she has been looking after this city and does not mind lending a helping hand to it’s inhabitant. But there is one problem – the existence of Catharsis is coming to an end, her soul is decaying and in a week she will die in case she cannot ascend to her ancestors. To do this, she needs a human guide who will extract demonic energy for the ritual. Annihilation finds their agreement fair and agrees.

[From Steam]