[Note: Since the beginning of the story feels bland and lacks excitement, I will focus on revising it first.]

Zero was a victim of the War of Harem.

Two years of his journey as a demon in a world resembling a game he once played ended in a tragic death. Fortunately, his soul returned to Earth.

On Earth, he was no longer Zero, the Shadow Villain, but Ernest, a runaway child haunted by an inferiority complex.

Until ...

"So, you wanted us to get married so that you could make me your furnace?"

He ended up being a furnace for his new wife.  

Behind his role as a furnace husband, he gathered strength and became a shadow once again, ruling the world from behind with the help of the system and skills from the previous world.

***

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