Travel Across Two Realms to Become an Emperor

The seven kingdoms stand side by side, Da Chu, Da Yan, Da Shu, Da Qi, Da Jin, Da Liang, and Nanyue. The seven kingdoms have been in conflict for hundreds of years. The seven kingdoms have been in constant war, decadent ethics, backward military systems, and poor people's livelihood. The six kingdoms have been encroaching on the borders of Da Chu all the year round, and they have conquered each other. Each country has its own background, veteran masters, elite defenders, and a coalition of aristocratic families. How can an idle prince make a comeback?