A yuri manga series written by Kouga Yun and illustrated by Minakata Sunao. It was serialized in Kadokawa Shoten’s Newtype magazine between the September 2012 and November 2016.
Title: Riddle Story of Devil (悪魔のリドル; Akuma no Riddle)
Author: Sunao Minakata, Kouga Yun
Language: Japanese (raws)
Volumes: 1-5 (complete)
Volumes 1 and 2 were found here, the rest purchased by me.
Volume 1: 
Download »86.21 MB mirror: mediafire »
Volume 2: Download »50.71 MB mirror: mediafire »
Volume 3: Download »45.34 MB mirror: mediafire »
Volume 4: Download »52.91 MB mirror: mediafire »
Volume 5: Download »43.48 MB mirror: mediafire »