Reborn as the Demon King, I Use Magic to Develop Star Destroyers!

After traveling through time, Roy found that he had become the Supreme Demon King who was killed by a brave man thousands of years ago. He didn't know that he was already the strongest in the plane. In order to deal with the risks of the other world and the threats of brave men that might appear. During the day, He imitated the Bone King and disguised himself as an adventurer to seek information in the human empire. He successfully solved many problems and threats, and even obtained a knighthood; night, Returned to Demon King's City to engage in construction, It sheltered all lowly races, popularized literacy, developed steam engines, researched magic firearms, established a magic Internet, and developed occupations such as takeout and rental. Finally, when humans saw the Star Destroyer floating in the sky of the Great Demon Kingdom, everyone panicked. The Human Empire Alliance finally decided: "It seems that the only way to do this is to let the empire's strongest warrior, Count Roy, lead the troops to defeat the Demon King!" Roy:? This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.