Transformation in Anime Crossover

She's Rem from Re:Zero, Boa Hancock from One Piece, and... chosen by a dimensional space, she becomes a Contractor, traversing different anime worlds, temporarily possessing the original characters. She engages in a battle of wits and deception with other Contractors who have also possessed these characters, trying to guess each other's identities. Who will survive to the end? Ochako Uraraka and Momo Yaoyorozu are locked in combat. Lucy raises her knife against Erza. Kuroko Shirai no longer yearns for her older sister, Misaka Mikoto's, body. Besides herself, any named character in the story could be someone else...