Leave the Last Light at Horizon.

The crown princess of a country was asked to go for a "holiday" in Bangkok before returning to her country to serve the king, her father. But what was hidden from her is that the king is in danger (someone tried to assassinate him) so to protect the crown princess, he kept her hidden in bangkok until the power struggles are settled. But being in Bangkok, the princess has to keep her identity hidden and so the state body guard of Bangkok who is have the responsibility of taking care of the princess have to both protect her and not get her identity exposed. And so that means they cannot dispatch bodyguards that are in charge of royal visit. Hence, they in the end hired a bodyguard who is very skilled to protect the princess. Of course, he doesn't know her real identity - has always believed that she is a millionaire's daughter. So this story revolves around them and but the question is a love of a princess and commoner is possible?