The Perfect Insider

Also known as: Subete ga F ni Naru, すべてがFになる -THE PERFECT INSIDER-

by Hiroshi Mori, Kairi Shimotsuki

Professor Saikawa and Nishinosono Moe go to camp on an island where the mysterious Professor Magata Shiki has a closed laboratory. They're curious about the murder of Magata's parents, and they manage to talk their way into the lab itself. While they are inside, a dressed-up corpse is shockingly propelled out of the door of Magata's quarters! It appears she was murdered, and she won't be the last... (Source: MangaHelpers)