Sovereign of the Three Realms (WN) - Chapter 34: Secret of the Nine Laughing Oceans

The story revolves around Charles Karino, a Levaamu Empire mercenary aerial pilot who mans the twin seater reconnaissance seaplane Santa Cruz. One day, he receives a preposterous assignment: to fly solo over 12,000 kilometers of enemy waters to protect a girl named Fana del Moral. Fana happens to be the next in line to the empire’s throne and a girl possessing beauty “equal to 5,000 beams of light.”

This is a standalone book. There’s another series under the name “To Aru Hikuushi e no Koiuta” (Love Song for a Certain Pilot) set in the same world, but in a completely different place and with different characters.

– Ulrezaj @ Mazui

Adapted to anime as “The Princess and the Pilot”

Cultivating his power by slaying demons and taming countless beasts, the emperor solidified his throne as the world's ruler. But not once in his life had he expected that his disciples would use research on demonology to sap the world tree's power and push the world to destruction.Trying to fix his mistake, he opted to use all of his cultivated power to cure the world tree and block anyone from sapping its power ever again. But in exchange, he was to lose all of his power.But...the worst had happened, his wife... had betrayed him.

Everyone had the right to choose his or her life. Maybe many people wanted to live an ordinary life, but Qin Sheng didn’t want to be a mediocre man. He had practiced martial arts under the guidance of his grandfather in the Zhongnan Mountains since he was a child. After two years’ wandering life, he decided to settle in Shanghai, so he contacted Han Guoping, a rich businessman, and took the job as his daughter’s safeguard. He thought that he only needed to protect Han Bing. However, things seemed more complicated. He got to know that Han Guoping offended a powerful figure and his life might be in danger. What would Qin Sheng do to help the Han family? Would he turn the tables?