Demoness Go See The Emperor

Demoness Go See The Emperor summary:

Na Lam ascends the throne at the age of fifteen. The empress dowager worries her son is too arrogant and selfish to be a good emperor. The empress dowager recruits Ling Fei, the daughter of a trustworthy ally, to moderate Na Lam’s arrogance.
Na Lam doesn’t want the commoner Ling Fei to become his empress. Ling Fei promises Na Lam that if he can defeat her in a duel then she’ll ask the empress dowager to break their betrothal.