Okay, this is going to sound weird but I'd like to read a novel where some characters get their hopes and dreams crushed while they fall into despair. (Ideally, the MC is the one who creates the said situation but it isnt necessary) I ve seen some such novels that depicted that (Dungeon Defense, Main Character Hides His Strength, Ouroboros Record and Warlock of the Magus World) That being said, no matter how long I look into the "depiction of cruelty" I cant really find something like that other than the said novels. So... any advice?
There were times when I was read Reverend Insanity, but there were so much of cruelity and selfishness that it doesn't make sense to me and I dropped. But you could like it.
Oh this one was cruel, annoyingly so... Not to the MC though, to the-- anyway, I had to drop it because I couldn't take the way MC acted.
Yo bast**! That's a cruel recommendation, I approve. Let them suffer! 5 out of 5. Glad I gave it a go!
I haven't read many LNs yet, but Overlord might fit. The MC is evil, him and his minions are the main sources of cruelty in the novels. A lot of storytelling is done from the POV of other characters who suffer from that to the point of conquest, death, or worse.
Mother of Learning. I would said thisworld is cruel, read it slowly and take a moment to comprehension. From an orphan being cheated by his guardian, corrupt and power hungry goverment, and immoral human experiment by necromancers, and mass murder people just for power, also reality of time loop when you spent a month befriend people just to know they would died at the end of month and recreated again and repeated, it's kind of torture.
My fiance is in love with my sister (I dunno if this is your type of novel but i'm still gonna post this) (Its story is literally the title, in which the girl repeats her life again and again to the day or moment her heart broke) (Its really sad, cruel for me)