My One-Hit Kill Sister

Asahi, a boy who loves video games, dies in a traffic accident and wakes up in another world. Eager to live out his fantasy of adventure, he quickly realizes his abilities are barely better than a background character's. When a monster corners him, his older sister Maya suddenly appears, saving him with a single blow. She followed him into this world and gained incredibly strong powers-but her love for her little brother borders on obsession. Now, Asahi, the weakest in this new world, must navigate life alongside his overpowered, overly doting sister.