The Promise of Chang’an: the story is set in the fictive Sheng country. He Lan Ming Yu is an honest and bright young lady. In her young years, she gets to know the 9th Prince Xiao Cheng Xu by chance. The two get along well and gradually develop feelings for each other. However, fate turns against them, and while fake news that Cheng Xu died on the battlefield spread, Ming Yu is forced to marry Cheng Xu’s third older brother and reigning king Xiao Cheng Rui . Cheng Xu helps Cheng Rui establish a great and stable country through continuous big achievements on the battlefield, but Cheng Rui is filled with jealousy towards his outstanding younger brother. When the truth about the death of Cheng Xu’s mother comes to light, Cheng Xu is determined to usurp the throne to take revenge.