The Truth of Magic - Chapter 38

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

In the territory of Zhao State, there are Liuxuanmen of the martial arts sect of Jianghu.

Su Yu became a handyman disciple who was just getting started.

Having obtained the sign-in system, he signs in at different places every day, and there will be various rewards.

Sign in at the center of the training ground and get the reward [Jiuyang Zhenjing]!

Sign in on the cliff near the residence of the handyman disciple and get the reward [Millennium Snow Lotus]!

Sign in in front of the sect library and get the reward [Lingbo Weibu]!

…

In this way, it was not until decades later that Su Yu discovered that he seemed to have surpassed the peak of martial arts and reached the level of cultivating immortals before he knew it…

Ninety-eight years later, a martial arts devil who was born out of nowhere made waves in the territory of Zhao, and no one in the martial arts world was his opponent.

Until this day, the martial arts devil killed Liuxuanmen and met Su Yu who was sitting outside the library, basking in the sun on a rocking chair…

- Description from novelbuddy

The Gura Gura no Mi is known as the strongest fruit in the world of one piece.