Just like what title says taking any genre/rec

I would appriciate it if you dont give me mainstream manga such a berserk,claymore,kenshin,snk:etc (already read them)

Preferly set at modern days (like mirai nikki,elfen lied:etc)
Also i didnt take rec from junji ito work (probably already read most of them) 🙂

Mmm, well, I don't know about your "extremely", that's kinda subjective, but I'll do my best with ones that carry the "blood and gore" tag and I think are decent enough (overall) to recommend...

Alyosha!, Anorexia - Shikabane Hanako wa Kyoshokushou, Death Panda, Franken Fran, Green Blood, Holy Knight (a stalled one, not completely scanlated), Kaibutsu Oujo, Kiseijuu, Mondlicht - Tsuki no Tsubasa, Superior Day, Toukyou Akazukin, Tokage no Ou and Yuureitou.

Good luck 🙂

Seconding Franken Fran, Kiseijuu, and Yuureitou.

And I also agree that I don't know precisely how "extreme" you want, so my recs are just those with a decent amount of gore, some regardless of how good/bad the overall story is.

6000
Übel Blatt
Ajin
Akame ga Kill!
Aphorism
Arachnid
Azumi
Black Lagoon
Blade of the Immortal
Bradherley no Basha
Deathtopia
Fire Candy
Golden Kamuy
Historie
Immortal Hounds
Innocent (SAKAMOTO Shinichi)
Kami-sama, Ki-sama o Koroshitai.
Kimi Shi ni Tamou Koto Nakare
Litchi Hikari Club
Mahou Shoujo Tokushuusen Asuka
Murciélago
Narutaru
Okitenemuru
Trash.
Vinland Saga (though not in the later chapters)

Apologies if you've read some of these before. I would suggest making your lists public (or just making lists in general, if you haven't yet) to prevent people from rec'ing stuff you've already read.

Yeah,youre right i've already read some ,but thanks for rec,i will update it someday the list 😀