Title is self explanatory. No preferences besides a protagonist with a secret identity or something similar like having two sides to them. A novel, webtoon, etc is fine. I just looove it when the protagonist is mysterious... (´ ▽｀).。ｏ♡
Oh and also, if someone can recommend me to something similar to A*D - Tenshi no Uso it would be great (^▽^)

Gokusen
Otokomae! Beads Kurabu
Tenshi ja Nai!!
Tokyo Crazy Paradise
Pairon

similar to A D.. maybe : Kuroshitsuji,Noblesse ,Shirogane no Ou,

                                     [No. 6](https://www.mangaupdates.com/series.html?id=61926)    🙂 

If I’m upset, hold me and tell me how beautiful I am.
If I growl, retreat to a safe distance and throw chocolate.

Thnx ^^ i will check them out...
Sadly i have already read kuroshitsuji, noblesse and no.6, but i will check out shirogane no ou 😀

Black Haze
Mahouka Koukou no Rettousei I can't stand the MC (and the manga overall too) but it's popular so you might like it.
Gun x Clover
Killer Stall
Mrs. Seonnyeo premise a bit like Gokusen
Kurenai Ouji

Himouto! Umaru-chan not really mysterious...but hilarious...-ly cute.

Superior and its sequel Superior Cross perhaps?

Is this me in a nutshell?
Pretty much.
[img]http://www.dragonflycave.com/wpay/ninetales.gif[/img]

Chang Ge Xing
Code Geass <<< i have only watched the anime and it was great
In Full Bloom (YON Jae-Won) << not sure if this one fits but it's a good manga to read
9 Banme no Musashi <<< i like this one very much but unfortunately i can't find volume 16 and up

Actually i have seen black haze ( love this series) and mahouka koukou no rettousei ( the novel for this series is better) but i will look ipnto the rest.

Yuureitou
Dendrobates
Basara
Lessa & sequel
Majin Tantei Nougami Neuro
Zombie-Loan

First thing that comes to mind is Nononono.