Kyuyaku Mother Ghoul
A prototype series to Mother Ghoul.
I guess Kiku Sugawara did this series first and it was originally called Holy Holy. This is only 2 volumes and feels like a smaller scale Mother Ghoul without a real ending. I’m glad that I read it because it fleshes out the backstory for certain characters who appeared in Mother Ghoul without any explanation. But I don’t think you need to read this before Mother Ghoul.
~dakazu