MILGЯAM: Jikken Kangoku to Kanshu no Shoujo

Gathered here are five "murderers," but each has lost their memories. The young amnesiac girl Es is their warden, tasked with investigating their "sins." As the pasts of these murderers are slowly revealed, what "punishment" awaits them in the end? When you learn of their crimes, will you be able to forgive them? This is the long-awaited comicalized spinoff of DECO*27 and Takuya Yamanaka's interactive music series.

(Source: Kadokawa, translated)