Isekai One Turn Kill Nee-san
You know that one series where the main character gets sent to another world, but his mother gets sent with him, and she’s super overpowered but also really doting to the MC? Yeah, replace “mother” with “big sister” and you have a good idea of what this series is about. Anyway, join Asahi Ikusaba and his big sister Maya as they have adventures in another world.