Katahane no Riku - Chapter 40.Nostalgic memories

So here's the pitch: I got reincarnated with Mangekyo Sharingan.Sounds overpowered, right? Instant win button?Except I can barely keep it active for thirty seconds without feeling like my brain's being microwaved. My chakra reserves are pathetic. My combat experience is zero. And the system that gave me these powers took one look at my situation and said “good luck” before fucking off into hibernation.Oh, and the Hero Killer—the guy who murders heroes for not being “worthy”—just decided my mom wasn't good enough. She'll never walk again.I know when he'll strike next. I know where. I've got exactly four weeks to train.Four weeks to go from “can't throw a punch without tripping” to “can survive a fight with a serial killer.”The smart move? Stay out of it. Let the pro heroes handle it.But I'm fifteen, angry, and apparently making life decisions with the wisdom of a shounen protagonist.At least I'm in General Studies. Low expectations.What does being a hero have to do with revenge anyway?

The mysterious boy Ling Chen is saved by a little girl as he lay on the street dying. Years later, he strikes a deal to save this savior-turned sister and enters the virtual world. In a future Earth where advanced warfare has forced nations to settle issues virtually or else suffer the consequences, Ling Chen bursts into the scene and goes from unknown to legend. Yet all is not as it seems, for Ling Chen has a dark past, and there is a greater mystery at hand behind this virtual world.

To save his terminally ill little sister, Ling Chen enters the newly released virtual game world and joins a small gaming studio comprising entirely of women. From now on walking upon his path towards the pinnacle. An ancient, evil item almost forgotten by history, the “Lunar Scourge” helps forge his unsurpassable legend, and causes him to unknowingly step upon a path that is destined to be punished by the heavens, the way of the Shura.

- Description from Novelupdates

This is the tale of Arin, a once kind-hearted and gentle child, now a man hardened by the cruelty of society and the brutal trials of life—a man transformed into a ruthless criminal, devoid of mercy. As his world was collapsing, fate transported him to a new realm. This world, more vicious and savage than his own, was steeped in magic and dark mysteries.Ironically, it was in this fearsome world that Arin, now an undead being, began to rediscover his lost humanity. Through battles and bloodshed, amidst the clash of sorcery and steel, he started to reclaim the compassion he once hated. This is not just a story of survival but a saga of transformation. Follow Arin’s journey as he rises to power, determined to become the ruler of this harsh world. In a twist of fate, he now seeks to save the very humanity he once wanted to destroy.

As a man who had lived for 20 something years and had always considered himself as a straight man, he woke up one day and found himself possessed by a stupid and cute system. Moreover, it was a gong-shou cultivating system?! Let’s see how a shou with raised hackles evolves into a (pseudo)queen shou, incidentally with a story of a hidden loyal dog gong.

- Description from Novelupdates