Martial Arts: I Am the Only Immortal in the World

The protagonist traveled back in time and became a boy of about ten years old. I'm afraid that if you pass half a year, even if you are 11 years old, isn't this funny? You are still familiar with each other. You can call people brothers after meeting them less than twice and have servants. People in that era are no better than you.

At the beginning, Goldfinger was just a space addition and fusion, but later it turned into a game manor. What the hell?