Could it possibly be another remnant of God? Memory modification of multiple powerful dragons plus Azad and sending some of the most powerful, famous, and influential dragons/wizards over to another world to undermine the factions?
Add in how a god got reincarnated into another world in a area that is becoming a nexus for powerful beings to congregate means there is something thats drawing those to there.
From that information it seems that their desires and searching for something has drawn them to the world.
Kanna was kicked out of her home after breaking the dragon ball and probably was searching for Tohru and ended up in the area where Tohru landed.
Lucoa and Fafnir were invited by Tohru and ended up finding a reason to stay in this world
Elma came to find and retrieve Tohru and ended up finding multiple reasons to stay
Emperor of Demise came to find Tohru and bring her back to their world.
Iruru wanted to find "Enemies to fight" and was drawn to where Tohru encountered Kobayashi then found a reason to stay
Kurumene came to find Iruru was defeated and sent back, when Tohru even arrived after he hurt Kobayashi he called out for Elma to help which meant he knew she was in the area.
Kimuin and Azad came to find Kanna and retrieve the dragon ball despite no one telling either of them where she had gone.
Jida chose Elma because, someone, suggested that Elma was the ideal candidate for their plan
Now Jida is kinda the odd one out but i guess "Searching" for the ideal pawn for their plan could count.
Now this brings up the question. why did Tohru, when fleeing from the god transfer dimensions specifically? From her backstory she wanted to be alone and free to do what she wanted which she did achieve after she met kobayashi.
