He accidentally fell into the underground world with his brother. Although he has the ability to protect himself, there is still a long way to go to achieve a truly perfect ending. The introduction was written blindly, and I don't even know what I wrote.
The original UT time and space had private settings. This is my first time writing an article, and my writing is terrible. The protagonist doesn't know the plot of UT, and there is no cp. Even if there is one, it can only be in the extra story.
Purpose: I hope everyone has a good ending