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.
Most of the setting will be 
determined by the gamemaster,
Im Großen und Ganzen bestimmt
der Meister, wie das Szenario verläuft,
La mayoría del entorno
lo decide el maestro del juego.
La mayoría del entorno
lo decide el master del juego.
Le maître de jeu décide
des grandes lignes du scénario,
Gran parte dello scenario è creato dal Master,
A ambientação é quase
toda decidida pelo mestre,
Хоть общее направление
сюжета и решает мастер,