Little Leiji grew crooked after devouring impure human souls, becoming a Mother Goddess who never did her proper job. To avoid becoming the "Mother of the Race," destined to bear children with the Old Gods day and night, she made a deal with her older sister, the "True Mother of the Race."
"Either have children with humans or come back and have children with the Old Gods. You choose. If you haven't given birth to a thousand offspring in five hundred years, I'll come and drag you back."
This is probably a story about an Old God girl roaming the world in search of people to have children with.
Kiana: Mom's love belongs to me alone!
Mordred: Mother, please think carefully about what caused the civil war in England!
Reimu Hakurei: Mom, you have money to support your mistresses and their illegitimate kids, but you can't spare a little more for me!
Gudako: Mom, who's that woman? Can I tear her apart with my bare hands?
This is probably also a story about a bunch of adopted daughters trying to stop their stepmother from having biological daughters.
Volume Two, the Legends of King Arthur, is being updated with great enthusiasm, meow meow meow.
This is a yuri novel.