Great primordial sin - Chapter 258

“Does the vengeance of justice count as a sin?”Fushimi Shika, burdened with a system, gives his answer: “Yes! But I will take on all sins!”Avengers chant his name, leaving behind his name. Thus, the world gains a notorious serial killer.A grieving father avenges his lost daughter by killing the true perpetrator;A husband takes revenge for his wife through a locked-room murder;A child who lost both parents makes a desperate gamble...Fushimi Shika shields these unfortunate souls who have lost everything, leaving his unique proclamation at the scene:“This is divine punishment, I am the divine punishment”...Years later, atop Tokyo Tower, Minamoto Tamako points a gun at her partner.“Although I don’t know how you did it, you are the mastermind!”Amidst thunder and lightning, rain pouring down, Fushimi Shika raises his hands:“How rude, Rabbit Officer, I am a messenger of justice.”

Luo Yi, a high school dropout in his original world, was isekai’d into the world of the Witcher 3. Starting out as a weak boy named Roy in the village of Kaer, Lower Posada, he was determined to grow stronger, no matter what it took. The first step toward becoming a legend was to kill. And his first kill was… a rooster. ‘You gain 1 EXP.’ Of course, Roy had his own cheat system like all the other isekai protagonists. His first step to becoming a legend started now…

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

- Description from Novelupdates

Kurogami Ichiro was desperate because he couldn’t achieve what he wanted when he once started his martial arts path at age of 8!