くわいなしょっく！

Sakaki Arima is a private detective. He only works on cases related to [url=http://en.wikipedia.org/wiki/Youkai]youkai[/url]. He has ability to strengthen himself by having sex with female youkai, but he need to do it regularly. One day, he received a strange letter with only one sentence: "I want to see the sun". At the same time youkai catgirl came to his office and forced him to take this task...