Returning to Another World, Being Singled Out by the Eldest Lady with a Stun Gun

[Single female protagonist + return + no system + no rebirth + male invincibility + female domineering + younger sister + sinister + plot + modern] Four years ago, the cowardly and incompetent Su Zimu was summoned to a different world to become a brave man and began his journey to defeat the Demon King. Four years later, Su Zimu, who had become famous, returned to modern society with all his supernatural powers. But I didn't expect that on the first night back... "Let me go, I was a man who had a 1v1 duel with the Demon King, and I almost didn't get killed by that woman alone!" ... After returning to normal life, Su Zimu found that this normal life seemed... Not so "normal" "What, my teacher is a demon slayer?" "What, my sister is a magical girl?" "What? My parents are not normal people either?" ... After a while, the girl who almost killed him alone snuggled into his arms "Mu Mu, you are my special pretty girl, do you understand that you want to stay by my side forever?" "My pleasure, Miss"