Niang-Niang

Niang-Niang (娘々(ニャンニャン)) is a 'bizarre magician' who dwells in a territory beyond a certain layer of the world.

Etymology
In Chinese, the term "Niang Niang" (娘娘) is an old-fashioned and respectful term for "mother." There are a number of Chinese goddesses that are sometimes called 娘娘, including but not limited to both and the, but more commonly designing , a  goddess of fertility.

Lance of Gungnir Arc
In that world where distance and time doesn't matter, destiny's hand has moved and allowed Niang-Niang to meet with Nephthys and the other magic gods that are in that realm as they discuss their plans after the events that have transpired between Othinus and Kamijou Touma.

Niang-Niang and the others later find Aleister Crowley ripping a hole in the fabric of the realm, which would mean that they could now appear in the existing world. Aleister later attack these "bizarre magicians" after they enrage him, though it is likely this was his purpose from the beginning when he entered the realm.