Toaru Majutsu no Index: New Testament - Volume 15, Chapter 1: Confrontation, or New Days — Turn_a_New-Leaf.

In China’s modern martial arts society, Wu Xinghe was history’s youngest grandmaster of martial arts. He was invincible. Because of a strange incident, he was reincarnated as Qin Wushuang, a poor aristocratic boy in an entirely different world with its own set of rules. With his strong will and passion, he began his journey to pursue the highest peak of martial arts!

Nine harmonic zither chords shook the universe, who dared to not acknowledge the lord?

The mortal body, metamorphosis, longevity, immortality, and eternal life. These five realms, step by step, reveal themselves in front of you. As a normal person, how can one try step by step to reach and open the door to eternal life?

Between the heaven and the earth lies the mortal body, the mysteries of metamorphosis, freedom of longevity, the power of immortality, and the hope of eternal life. A story filled with endless new magic, a new world of immortal styles, people, demons, gods, fairies, magic, kings and emperors. A world of love and hatred, revenge, and mystical battle, all in “Eternal Life.”

- Description from Novelupdates

220 years ago, in the legendary Dragon Demon War, Hero Azell ended the war by killing the evil Dragon Demon race’s King Atein. He was able to save the population, but as a consequence, he was cursed. While he was dying, the high magician suggested a gamble that might save his life.