There Will Always Be Protagonists With Delusions of Starting a Harem - Chapter 29

Anyone who could construct a stable Spell Model could become a Wizard — that was the Wizards’ ultimate secret! Having been given a new life as the son of an aristocrat and armed with a super quantum computer from his past life, Spell Models came as easily as breathing to Merlin. With this overwhelmingly huge advantage, would Merlin become the greatest Grand Wizard of all time?

- Description from Novelupdates

Three years into Qin Yu's marriage, his wife and in-laws all hated him.

He was summoned to save the world… but his greatest threat isn’t the Demon King — it’s the women who love him.Kai Veyron was just a delivery guy on Earth. But in the magical world of Aethria, he’s “The Chosen Hero” — gifted with ridiculous, godlike powers that he can’t control and didn’t ask for. He defeats monsters by sneezing, trips over relics that explode, and somehow charms every powerful woman he meets.Now surrounded by a beautiful, deadly harem — a tsundere princess, a cold-blooded assassin, a genius mage, a seductive demoness, and a broken childhood friend — Kai thinks he’s finally found purpose, friendship… maybe even love.But peace has a price.As whispers of prophecy grow louder, the women begin to ask the unthinkable:“What if the hero himself is the final calamity?”They laugh with him by day… and plot his death by night.And the worst part?Kai already knows.And he still protects them — even if it means his own downfall.

The apocalypse descends, zombies and monsters appear, followed by System Leveling, which grants skills to all survivors.With the collapse of law and order, some become powerful while others remain weak, and so the dark ages begin.