Isekai One Turn Kill Neesan: Ane Douhan no Isekai Seikatsu Hajimemashita

Both shows take place in another world where the MC is a guy who is not very strong, and a family member that's overpowered pretty much making the guy useless when it comes to adventuring. 

The idea of calling incest can be similar in these animes. Love between brother and sister which is considered to be taboo is shown in these two animes. The characters want to take their siblings relationship to much further like a married couple. Though "One-Hit Kill Neesan" is not as sexual as "Yosuga no Sora" their main theme happens to be similar. I warn you One-Hit kill Neesan can become boring compared to Yosuga no Sora but, as it is an isekai-adventure slow anime, give that a little time it won't disappoint you. Also both of them can be considered harem. 

These two shows are very similar in the way that if you replace the Sister with Mob and The Scammer with the Boy MC, you get almost the same show, both animes feature funny comedy and fun almost slapstick gags every episode.  

These two animes are only related to one strong aspect that is onee-san loving their younger brother in a romantic way and wants to make their relationship more than just siblings. Only the main theme of these animes are connected, other than that they are totally different. As "One-Hit Kill Neesan" is an isekai action anime (not much ecchi) and "Kiss x Sis" is a romance-drama (100% ecchi) anime . But there might be another thing similar, both of them can be described as Harem.