I! Cleaner! - Chapter 466 - 404: A Wondrous Number

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

- Description from Novelupdates

As Shin Youngwoo has had an unfortunate life and is now stuck carrying bricks on construction sites. He even had to do labor in the VR game, Satisfy!

He died on the wedding of the girl he had a crush on, after a long and successful career. After convincing Yama to send him back to the world, he decides to fix the areas in which his life went wrong. Realizing the lack of love and romance in his past life, he sets out to conquer the hearts of various women.

In a world where dungeons loom like dark secrets and monsters stalk the land, Rem’s awakening shattered the status quo. A surge of raw power flooded his veins as the Monster Monarch System bound itself to him, unlocking a terrifying potential.Each heartbeat echoed with the promise of countless souls waiting to be absorbed—skills, abilities, and monstrous strength ready to be claimed.Fuelled by an insatiable thirst for power, Rem set out on a deadly quest, driven by one singular goal: to rise above the chaos and stand at the pinnacle of the world. With nothing but the deadly abilities granted by the System, and a burning will to crush any who dared stand in his way, he carved his path through savage lands and ruthless mages.The hunt for strength never ends. The battle for supremacy has only just begun. Rem’s eyes are set on the throne of the Monarchs, and the Monster Monarch System will ensure nothing stands between him and his destiny.The grind was eternal...