One Piece: Fist of the World - Chapter 40: The Navy’s Attack

The world was once at war with 10 alternate worlds. This was known as the Concept War and our world won 60 years ago. All of this was concealed so no normal people are aware of this fact in the current time.

After the death of his grandfather, the high-school student Sayama Mikoto is suddenly summoned by the giant corporation IAI. He learns this world is headed for destruction due to the acceleration of the Minus Concepts. To prevent this, negotiations must be undertaken with the survivors of the other parallel worlds so their 10 concepts can be released.

And so Sayama is caught up in the final battle to clean up after the Concept War which left behind so much enmity.

Hu Feng, a high school student, accidentally embarked on the road of modifying the world.

Fear breaks the boundaries between dreams and reality, and it is impossible to tell which is reality and which is illusory. When the nightmare really comes, no one can be alone.

This is both a danger and an opportunity.

- Description from novelbuddy

Chu Yang, the Ninth Master of the Nine Tribulations Sword, sacrificed almost everything he had for the sake of improving his martial arts, including the love of his life. After spending three years locating the fifth fragment of the Nine Tribulations Sword, he was ambushed by all sides at that very place. Mortally injured with no means of escape, Chu Yang executed a sacrificial technique by plunging the Nine Tribulations Sword into his very own heart. “With the blood of my heart, ten thousand tribulations will collapse!”

After witnessing the death of all his ambushers, Chu Yang’s vision began to darken. At a distance, moments before his death, he saw the mastermind who had plotted his downfall — Mo Tian Ji. With that, his eyes finally closed.

However, with a start, Chu Yang once again awoke to find that he had returned to when he was sixteen years of age! Furthermore, the Sword Spirit of the Nine Tribulations Sword now resided within his Dantian, the energy center of his body! From that very moment, Chu Yang would then begin to right all of his past regrets, and carve his very own legend by fulfilling his destiny as the final Master of the Nine Tribulations Sword, and defeating the Heavenly Devils beyond the realm of the Nine Heavens Continent.