In order to cheer Haruto up after his anime was such a flop, Itsuki gets him as well as Nayuta, Miyako and Chihiro together so they can play a TRPG. Itsuki usually plays girls in games, but for some reason, Chihiro makes out their character to be Itsuki’s character’s little sister, which leads to Nayuta and Miyako also making their characters sisters of the other two. Haruto becomes the GM and does whatever he wants.
Those are probably TRPGs 
based on the Cthulhu mythos.
Ich nehme an, du sprichst von
Cthulhu Pen-&-Paper Rollenspielen.
Creo que ese es el juego de rol
sobre Cthulhu.
Creo que ese es el juego de rol
sobre Cthulhu.
C’était sans doute des jeux
inspirés du mythe de Cthulhu.
Quelli probabilmente
erano TRPG basati sui miti di Cthulhu.
Esses provavelmente são RPGs de
mesa baseados no mito de Cthulhu.
Игра, видно, была на основе
мифологии о Ктуллху.