Devil's Spiralling Staircase

A strange girl meets an even stranger boy.
Things get unusual when rich girl Yamiko Hateshinai meets Akumano Rasenkaidan. She becomes a magical girl looped into his string of contracts. Along with some other girls she knows and becomes "friends" with.


Yamiko Hateshinai is a girl who obsessively collects things.
No one would suspect that she would acquire a mysterious "devil" who offers to make her a magical girl meant to save the world from invaders from another dimension.
The only problem?
She isn't Akumano's only contract. Can she work with her more or less partners despite their issues? Or should the invaders wait for their "enemies" to kill each other first?