Re:Zero kara Hajimeru Choukyou Seikatsu ~Saimin Choukyou Rem~

Defeated by Petelgeuse, Rem's memories are altered by the power of the "Unseen Hand", which makes one of the Witch Cultists appear to Rem as "Natsuki Subaru".

The fake Subaru's job, given by Petelgeuse, is to train Rem to become a sex slave of the Witch Cult within 5 days.

[Edited from HBOX.JP]