Sapphire-san To Sukebe Suru [English], an hentai doujinshi parodying the Last Period game (it’s an RPG), by Booch
Update: lol, bad timing for a scanlation to pick and release, I have to remove it from hentairules, because, in parallel, here is what came up:
https://twitter.com/ShikimayaPub/status/864342009057689600