Not sure but could be supernatural or fantasy
Had a gray or white background and there was a single guy on the left side of the cover
The guy had dark hair (possibly black ) dark clothes and I think dark red eyes (not so sure I but I think I can remember him holding a weapon maybe a gun or a sword and only the upper side of his body was in the cover photo ( it wasn’t a full body drawing )
Also pretty sure it’s not that popular and it’s a manga not a manhwa
If there’s any other ways for me to find it based on there descriptions plz lmk it’s annoying me so much