MTL - Entertainment From Divorce - Chapter 6 I'm going to sing a song

Amakawa Haruto died before he’d the chance to reunite with his childhood friend who disappeared five years ago. Rio, a young boy living in the slums seeks revenge for his mother who was murdered in cold blood in front of him when he was only five years of age.

There exists the earth many knows of and there exists an alternate world. Two people, each with their own backgrounds and values. For odd reasons, the memories and personality of Haruto, one who should have died resurrects in Rio’s body. As the two are confused over their memories and personality fusing together, Rio (Haruto) decides to live in this new world.

Along with Haruto’s memories, Rio awakens an unknown but special power. If he’s to use it, it looks as if he can live a better life, but before that, Rio encountered a kidnapping which results in involving the two princesses of the Bertam Kingdom.

After saving the princesses, Rio is given a scholarship to attend the Royal Academy, a school for the rich and powerful. His background being a poor orphan who once lived in the slums, the school full of nobles was rather a detestable place to stay at.

With the birth of Romo’s 18th generation descendant, something beyond the realm of consciousness has been awakened!

A modern-day antihero, who was infamous for his devious acts, dies in an explosion meant to take down a powerful criminal syndicate. Waking up in a world of sword and sorcery, he finds himself possessing a fragile, powerless body with a strange “System” that seems broken. Initially thinking he's doomed, he learns that by pretending to be weak, he can manipulate others into revealing their secrets, granting him abilities they possess. As he rises in power, he discovers that the System was intentionally sabotaged—by none other than his own future self.

This novel is also known as Don't Mess with the Dark Princess

When trash becomes a genius—one word: Fierce! Two words: Two-faced! Three words: Too heaven defying!

She is the foremost and outstanding armament refining master. Passing through a dynasty, and became a publicly humiliated and bullied Third Young Miss. Ancient beasts, too outrageous? Obediently become a docile pet, or I’ll make you into soup!

Ninth rank talent, rare talent in a thousand years? She was born with a godly constitution, crushing all geniuses!

Peak level Profound Grade Armament, beyond priceless? Sorry to embarrass, but the bowl she uses to feed the cat is already at the God Grade….. she possessed a pair of eyes that could see through everything, yet she couldn’t see through—him!

Merely exposing his demonic smile, Prince Mou lightly loosened his belt: “Can’t see through? Do not fret, you can slowly view when you return to the room. I’ll allow you to scrupulously inspect from head to toe.”

- Description from Novelupdates