Well this seems like half a story.

True, I do question what sins to become youkai warrants death.

True, I do question what sins to become youkai warrants death.

That by itself was covered by official works. Remiu considers becoming a yokai to be distablizing. Yukari jumped through some hoops to keep Kosuzu from being literally (because that it is normally a euphemism for beating someone up) exterminated.

It seems like this was written in the middle or beginning of Forbidden Scrollery, since it covers the same story/concepts that the series ended with.