Naruto System in One Piece - Chapter 486

Catching arrows, running up walls, crushing boulders and bending metal, these are but petty parlour tricks in the eyes of martial artists. But where can a genuine martial artist stand in an era where martial artists are nothing more than a myth?

【Brand New Setting】【Fully Developed System】When you awoke, you had become an official known as “Minister of Agriculture” in a fantasy game.“Dynasty's Prosperity” version: You diligently cultivated the “Seasonal Order,” from “Harmonizing Winds and Rains” to “Summoning the Winds and Commanding the Rains,” from “Bountiful Grain Harvests” to “All Things Flourish,” commanding the seasons and quietly developing.You achieved minor successes, joined the army on expeditions, and controlled the “Four Books of Agriculture.” You froze thousands of miles of great rivers to pave the way for the army. With “Miasma” you slew enemies, “Fog Shadow” obstructed tens of thousands of troops, establishing unparalleled military exploits and rising to the position of Director of Agriculture, secretly seizing the fate of the dynasty, all falling into your hands.“Spiritual Energy Resurgence” version: You nurtured “Mountain Spirits and Wild Creatures”: Twin lotus make you invulnerable to both water and fire, the Seven Star Sword cools the light across Nineteen Provinces, Parasitic Species feeding on living beings, Void Species rooting in the void to absorb the Spiritual Energy of heaven and earth... You established an inner scenic area, cultivated immortal species, with “Grand Taiyi Lotus” replicating en masse! “Ancient Tree of Life” immortal and indestructible!“A true seed falls into the Dantian, can nurture spiritual sprouts for ten thousand years, one day when the cultivation is complete, my life is governed by me, not by the heavens!”“Heart fire shines like the sun, kidney water is the source, spleen stores earth, lungs refine through metal, liver sustains with qi. Using the body as the foundation, nurture original species, foster all laws, achieving the status of Shennong Dao Master !”

In this world, orphans or just anyone without any hope for this world can apply to become a “walking target”. Their sole purpose is to be a practicing dummy for the students of the sect who train to become “Demon Hunters”. These students need “walking targets” to test their training on living, walking beings of flesh and blood.
In exchange, they will be provided with food & shelter.
Their existence value is lower than a slave, but if they manage to survive a few years they can receive a life long pension.

Xiao Han is such a “walking target”. One time he witnessed a powerful Demon Hunter disposing a demon. When the demon died, a fragment of the demon that managed to escape entered Xiao Han’s heart. No one saw that, and even Xiao Han himself only felt some discomfort for an instant.

But that thing in his heart soon gave Xiao Han visions, and the first one is of a cultivation method which allows Xiao Han to absorb damage to enhance his body. A perfect cultivation method for a “walking target”.

- Description from Novelupdates

A skilled but unfortunate modern-day assassin was killed in a freak accident. However, he soon found himself summoned to another world by an evil wizard, who had him possess the body of a boy as an experiment. After successfully planning the evil wizard’s downfall, he used the wizard’s body as a springboard to gain influence and power in his new world.

- Description from Novelupdates