Playing with Technology Through Time Travel

After opening the ancient well in his backyard, Li Min's life changed! The Sixth Prince Li Min? Li Min, the otaku of the 21st century? Since he can travel freely between the two worlds, what kind of life should he choose? Harem? Fighting for hegemony? Trickery? Is that all? No! With modern technological advantages, he will build his fiefdom into the world's economic center, and the world's map will be filled with his colonies...