One Piece: I'm Destined to Be the Son-in-Law King! - Chapter 16: Start ’Em Young - Raising Your Future Wife

A terrible calamity has fallen onto Zhang Fan, not only becoming one of the three survivors of Grass Temple Village, where everyone else was horribly massacred, he was also tasked to carry one of the most evil artifacts, the Sinister Bead, and taught one of the most secret teachings of the Skysong Sect, the Brahmin Wisdom. Now he cultivates in the Jadeon Sect, his knowledge and possession will draw him into a chaotic story where he will have to carry some of the greatest burdens of the Martial World.

This is a fan work of “Magic Forbidden Book Catalogue”, and some settings of “Puppet Circus” are added at the same time.

A traveler from a circus enters Academy City to study and live as a puppeteer; at the same time, he secretly fights against the enemies who keep coming to seize the original magic book in his hands, and protects the safety and peace of Academy City by the way.

…The Third World War? Does the mainland dare to call it “World War” without playing?

- Description from novelbuddy

After becoming #1 in the world after playing a grand strategy game as the most difficult faction on immortal level difficulty, MC receives an invitation to compete in an even more challenging game which takes the MC into the world of the game itself, but as it's weakest lord who will die two days later that appears only as a cutscene in the tutorial as first of many deaths to rock the continent until only one survives to proclaim a new eternal empire.Can the MC use his game knowledge to successfully survive his impending doom, and rise from the ashes to reclaim the glory he'd won before?

The main character is reborn as a character from a game he played in his previous life. This character falls into ruin along with the villainess, spending the last of their years together. A man named Kururi Helan.