Saikyou Onmyouji no Isekai Tenseiki

In both cases the protagonist reincarnates himself intentionally, both are too op and somewhat similar how they act. Side characters are also alike. Where there was a bit of twist at the last few episodes of Saikyou Onmyouji , the other one ends the show in quite a dull manner. Both of these animes follows the same premise overall.  

Both are about someone who was the best and got betrayed then reincarnated in another world. Both are a good watch. 

Guy gets reincarnated into a new word which has magic in it. Becomes overpowered but hides his true identity from others. Both of them are cautious of their new world, want to live an easy life and gets allied with female acquaintances. Although these two animes are not quite of similar story setting but both are enjoyable in similar aspects. Sometimes it can be a little slow going story but they wanted to cover the story perfectly so can't complain. If you like one be sure to check the other out. 

both have onmyouji (ancient japanese exorcist) as its main character "onmyouji" is historical fiction with fantasy themes "Saikyou Onmyouji no Isekai Tenseiki", as in its title, is an isekai 

The MC in Eminence in the Shadow is trying his best to be a sidecharacter, he is also very very OP and the biggest no Simp, just like in Saikyou Onmyouji no Isekai Tenseiki.  

Similar plot, reincarnated OP MC meets harem.