Paragon of Destruction - Chapter 194 The Way Back

A former sporting rifle shooter genius transforms into the ‘Juvenile Butcher’. While originally supposed to have received the death penalty, he was instead fortunate enough to have entered a secret and highly regarded armed force, throwing himself into the ‘Nirvana Project’.

After a period of 10 years, he now has time to freely recover. Having trained until he had excellent military and martial skill, he sweeps through various military districts and returns back to his hometown. Under the monitoring of a beautiful female cop, he re-establishes his family’s bodyguard service, protecting beauties and moving unhindered, his achievements causing the fame of his outstanding, god-level bodyguard service to resound across the world!

- Description from Novelupdates

Cairn is a prince who is already tired of ruling. Faced with an imminent coronation and an overbearing father, he wants nothing more than to drown his responsibilities in cheap liquor and poor decisions. With the help of his sister, he hatches a plan to escape the clutches of the throne once and for all. It all goes terribly wrong, and Cairn finds his priorities shifting in the face of unimaginable tragedy. The change of heart comes too late, however, and Cairn dies. He reawakens to find himself transported ten years in the past. He immediately begins to plan for the future, only to discover his killer has somehow followed him. To succeed, Cairn must unite the kingdom and discover the motivation of his killer, using as many tries as it takes. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++I exhausted pretty much every time loop story ever written and decided to write my own. You'll see a few similarities here between this story and some existing stories, at least initially. There's a lot of inspiration drawn from both MoL and Re:Zero, though in terms of pathos and darkness, this story leans more towards the latter. Be warned, it is something of a slow burn. The main character will grow and become powerful, but a theme of this story is that power comes slowly and often at great cost.