My older sister is a slovenly, hikikomori, and socially awkward shut-in.

To rehabilitate her, I purchased a "game that can perform personality correction." Basically, it's a monster-slaying game, but by linking a person's consciousness to an avatar, the in-game elements supposedly influence the person's personality.

I immediately started the game after linking my sister's consciousness. When I selected the tutorial to acquire skills, she started performing fellatio and sex with a mob character. After the act, she acquired the "Fellatio" and "Mounting" skills, but... what will happen to my real sister?

Suddenly, my sister bursts into my room. "I, I don't really understand... but... I can't stop feeling horny..."

Is she in heat and lost her mind? I was forcibly pushed down—.

Having confirmed its tremendous effectiveness, I decide to proceed with the mission. Little did I know that my sister would change beyond my imagination in the future...