My One-Hit Kill Sister

Isekai One Turn Kill Nee-san: Ane Douhan no Isekai Seikatsu Hajimemashita

Asahi loves the idea of magical fantasy worlds. And somehow, he’s transported to one! He’s eager to explore and use his new abilities, except he learns he doesn’t have any. But his older sister Maya is in this world too, and she ends up having the strongest cheat skills imaginable! Now, Asahi starts his new life with a doting sister who can kill any beast with one hit. (Source...