A fourteen-year-old boy was naughty and got into trouble. A crack suddenly appeared in the wall of his home. He wanted to hide it from the outside world and tried to repair it by himself using the weird three-legged cat technique. When the ground actually broke, he discovered an underground path. How can a curious child be sorry to the audience? He went down. Weirdly, I find myself in a world where technology is much more advanced than the 21st century, but the thinking is shockingly backward. Is this the third dimension I live in? After that, many unexpected and strange events happened, and dreams that were previously thought impossible were realized. But is this really a simple time travel? The cracks on the ground healed automatically. In the original world, he might have been reported as news about "the mysterious disappearance of a young boy at home" or something. It's impossible to go back anyway, so boldly seek the truth!