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

This isekei series is centred on Asahi Ikusaba, a high school student who dreams of living in a world like those in the games he plays. One day, following an accident, he wakes up in one! He has seen plenty of series like this so expects to have ridiculously powerful skills... he soon learns that he doesn't. As he looks doomed in a confrontation with a powerful monster he is rescued by his sister that has followed him to this world and has the sort of powers he was hoping for. She also has strong, inappropriate feelings for him. The adventurers' guild, believing he killed the monster, give him a higher rank. The pair end up doing various quests together and meet up with various other, mostly female, characters. Yes; it does end up being a harem series.

This certainly isn't a must see but that doesn't mean it isn't a fun watch. There is plenty of enjoyably action and the characters are entertaining. Inevitably there is plenty of fan service; this is mostly limited to revealing costumes so there was never any need for intrusive censorship that many series suffer from. The character designs and animation are both good. Overall I'd recommend this to fans of isekei series who don't mind a bit of fan service.

These comments are based on watching the series in Japanese with English subtitles.