FYI, these are characters from the video series Hifurin club by ND on Niconico which is basically futa's Serious Scare: Sealing-Rin but with more horror elements. (ND was inspired by futa in the first place)

No english translation for the video series as far as I know but ND did upload some parts on his pixiv account as novels so feel free to load those up and put them into Google Translate if you wanna read them.