Ok! Here's a variety of stuff then! (Warning: some may include dark themes/images)
Phantom Tales of the Night
Kings' Viking
Clover (tetsuhiro Hirakawa)
Three Days of Happiness
Mononoke (this one also has an amazing anime)
To You, The Immortal
Kiichi!!
Kiichi!! VS (sequel to the previous one)
Totsukuni no Shoujo
Migi & Dali
Shokuryou Jinrui
Shokuryou Jinrui Re (sequel to the previous one)
Gangsta.
Oyasumi Punpun
Bless
Jojo's Bizarre Adventure
Kamonohashi Ron no Kindan Suiri
Pet Shop of Horrors
Uzumaki
Hunter x Hunter
Musuko ga Kawaikute Shikataganai Mazoku no Hahaoya
Vinland Saga
Beck
Death Note
Innocent (sakamoto Shinichi)
Saint Oniisan
(These next ones are manhwa/manhua if you're interested)
Eleceed
Papa Wolf and the Puppy
Lookism
Winter Woods
Bastard (hwang Youngchan)
Nowhere Boy
The Boxer
Miss Guillotine
Unhinged
Nan Hao & Shang Feng
manga to cure my reading slump