I Married You to Save the World, Do You Believe It?

The mysterious boy worked as a house-call son-in-law for three years and pretended to be a grandson for three years. After being divorced, he completely let himself go. The silver needle in the left hand saves the world, and the flying knife in the right hand defeats the enemy. He talks a lot about cheating and has many tricks. Enemy, kill! Goddess, push it down! Travel thousands of miles to find your relatives and save your sister, slay demons and sweep across nine continents!