[Looking for Manga] Mao reincarnation.

[caffeinateddrugs]

Hello I vaguely remember a manga similar to Maou Gakuin no Futekigousha [https://mangadex.org/title/31962/maou-gakuin-no-futekigousha], but the Maou is trying to hide his identity, but not very well, and one of the teacher used to be his older sister/cousin and he's afraid he's going to be found out because of how scary she is.

 

[4V29LN0n]

Most likely you can go through the “reincarnation” tag with either “fantasy” or “adaptation” or “magic” tag. Plus the setting the original language. There can’t be that many of them.