Arifureta Shokugyou de Sekai Saikyou (WN) - Chapter 174

In a world ravaged by radiation and the remnants of war, Dylan is far from a classic hero. A lieutenant with a tainted past, he's just trying to survive the ruins of a dying world... until the day he wakes up bound and surrounded by the mutilated corpses of his comrades.Captured by monstrous creatures, he soon realizes he’s been transported to another world. A world far more dangerous, far more brutal—where only the strong survive, and even monsters are hunted. Saved in extremis by Maggie, his commanding officer, he begins a desperate escape. Their only hope may lie in their encounter with Élisa, an elf abandoned by her kin, and their discovery of a mysterious power: anima gems—stones imbued with spiritual essence that can enhance body and soul, and unlock the path to awakening.No One under 18 admitted

To save a doomed fantasy world, I killed the main characters, then destroyed the game world, and fell into another timeline as the academy's top seat and rival to the protagonist.Now, I'm trying to save the world and steer it towards a better ending…But I'm the final boss.

The hearse with the weird odor slowed to a stop before the entrance. The sound of pebbles could be heard bouncing on the ceiling. There were footsteps coming from the corridor, and there seemed to be someone sawing next door. The door knob to the room rattled slightly, and the faucet in the bathroom kept dripping even though it had been screwed shut. There was a rubber ball that rolled on its own underneath the bed. Wet footsteps started to surface one after another on the floor.
At 3 am, Chen Ge held a cleaver in his hand as he hid beside the room heater. The call he was trying to make was finally answered. “Landlord, is this what you meant by ‘the house can be a little crowded at night’‽”

- Description from Novelupdates

Born with the fate of a slaughterer, but all he wanted to do was help.