What's this manga

Manga about 100 frankenstein like creations, its was like black butler but gender swapped. The last or first creation is the most powerful and she and this younger boy team together to find and kill the other 99. She made a deal with the boy that once all 99 of the other creations die then she can take his eyes or something like that.
There was a chapter where it seems like the creations killed all of the boy's family and relatives so he's the last one.
Thats all I remember pls help thx