I Fabricated the Techniques, but my disciple really mastered them? - Chapter 381 - 218 Undying Golden Body,

Kai of the Sorcerer’s Tower is one of the last mages left, barely surviving in a world ruled by creatures of the dark — where the era of mages ended, and most of the lands got contaminated with dead mana. To save his world and fulfil his master’s last wish, he put himself through a forbidden ritual, risking his soul being ripped into pieces to make his way into the past. In an era with abundant mana — an era yet to enter the Golden Era of Magic. Things go wrong, of course, as they always do, and he finds himself thousands of years before the world fell to mana contamination — in the body of a young lord, Arzan. All is not well, though, as the young lord was murdered by someone right at the cusp of a beast wave threatening the territory, while larger threats loom on the horizon. There was a lot to do for Kai to regain his former strength in this time of primitive technology, but then again, he might just be able to change that.

In Academy City, magic and science coexist in an unwavering power struggle. Toma Kamijo, an academically-challenged student in Academy City, wields the power of the Imagine Breaker in his right hand, which allows him to completely negate all supernatural powers – as well as his own luck. When he happens upon a mysterious nun named Index, whose mind has been implanted with the Index Librorum Prohibitorum – 103,000 ancient texts banned by the Church – Toma’s luck is about to be pushed to its limits when he finds himself in the middle of a war he never expected!

Crossing to One Piece world, he became Roger’s younger brother.

Unexpectedly, Gol-D-Roger who was in his fifties had a teenage brother. But he was so weak.

Fortunately, at the age of sixteen, he actually found himself with a possession soul system.

He had attached to the master IP man, also to the White Phoenix and to Ge Nie with his strong ability of the Hundred Step Flying Sword.

If you think that he can only Purchase these? Then you’re wrong!

Pain, Itachi, Ichigo Kurosaki, as long as there is money, any soul can be Purchased.

- Description from Novelupdates

Ye Chen, once the unrivaled immortal standing at the pinnacle of the cultivation world, fell at the final hurdle—his last heavenly tribulation. Struck down by the wrath of the heavens, his body was destroyed, his cultivation shattered. Yet, instead of vanishing into oblivion, his soul defied fate itself.When he opened his eyes again, he was no longer in the vast cultivation realms but in the familiar yet distant world of modern Earth—inside the body of his younger self during his high school days. Armed with the knowledge and power of an immortal, he would rise once more, overturn destiny, and reclaim his supremacy in this new world.