There's a synopsis in description, but I will give you a bit more insight of this LN. Elves and humans was on neutral term. They didn't try to provoke each other. But, everything become different when elves decided to invade humans. And they invade humanity to make them become their slave and monster. Simply, elves didn't think humanity as their equal. Yeah it is an extreme racism based on power of a race.
Then there's a human boy that lost everything to elves. His BF betrayed him and kill his
village acquaintances and proceed to make them monster
. His family is slaughtered by elves in front of his eyes. He was 'almost' died because of them. And what do you think he will do? REVENGE. Kill them and give them his grief. Break their soul and bodies. Bury them and send them to hell their belong. That's all he thought. The journey of revenge has just began.
Well, it's my personal thought, but it's a novel that is out of normality of JP LN. Dark and very heavy. I recommend this LN if you liked Revenge, Dark, Gore, and Anti Hero Protag.
Think Kratos's Personality from God of War and combine them with A Meticolous MC and apathetic to stranger's doings of Hajime from Arifureta, but much much extreme.