Kureha One

Haruka was a succubus who came from the demon world to kiss human girls and suck their energy. However, she didn't meet a single one in the street until sisters Yuuna and Sana asked her if there was something wrong. Haruka took an immediate interest in them and wanted to immediately drain their energy, but it didn't go exactly to plan and she just looked like a strange person.
In the end, Haruka somehow ended up freeloading at their place and spending a normal life with them. It was something which she wouldn't have experienced in the demon world, so she thought that it would be nice to be like this forever. However, Sana confessed to her one day and she realized her feelings towards them. She had never fallen in love before, so she was at a loss at what to do. It was a strange love triangle, but the days that they spend together are ones of happiness.