I Eloped with a Runaway Princess, Only to Discover She's the Villain

Transmigrating into a game I made should be a happy occasion.

Having a considerate transmigrator sister who shares neither parent with me should be a good thing.

Saving the world as the chosen one should be an adventure.

Eloping with a princess should be one of life's great blessings.

Being forced by the queen to marry her and soon become king should be a cushy job, too.

But when all these things pile up on one person, it's no laughing matter.

"Maybe if you're not careful, that villainous princess will kill you."

"But don't worry. I'm sure you'll win her heart in this ridiculous adventure, as easily as saving the world."