You have been brought into a mansion where strange things are happening. It all begins when you are kidnapped by the mysterious oni. And this is just the beginning of your strange new life. 

Your first reaction is to try to get out of this place as quickly as you can, but the truth is that you are not in any danger. You are safe in this place and you need to stay here. But there is something that you need to know, and that is that the oni is not the only one that can take you. You are also in danger of being taken by other oni. 

What is oni? And who are they? The answer to these questions is not only in this world, but in another world. And this other world is so different from ours that you can not even imagine how it is possible that such a different world exists.