Densou Genshi Mirukyua

Natsuki's older sister is an avid player of the online game "Real Breaker," but a business trip prevents her from participating in an event where the ultra-rare "Mirage Stone"—an item that can grant any wish—will be released. She convinces Natsuki to play in her place using her female character, and after a suggestive farewell, leaves him to it.

When Natsuki starts playing, he is suddenly pulled into the game world, transforming into his sister's female avatar. Immediately captured by a tentacle monster, he endures repeated assaults, but finds himself curiously enjoying the sensations of his new body. He is rescued by a beautiful female warrior, and together they embark on an adventure filled with erotic encounters and dangers.