DEMI GODS AND SEMI DEVILS BOOK 3 OF 5 (Breaching The Formation) by Jin Yong

Between the period of 960-1127, Northern Song Dynasty is at war with the Liao dynasty. Three sworn brothers; Xiao Feng, Duan Yu, and Xuzhu join forces to bring what's right and just in the martial world. The three of them each have their own characters, adventures, love stories, and pitiful parental backgrounds which mold them into great martial art heroes.
Demi Gods Semi Devils consists of 5 books :
1. Adventures Of The Youth - featuring Duan Yu
2. Shrouding Screen In Suzhou - featuring Qiao Feng and Duan Yu
3. Breaching The Formation - featuring Qiao Feng
4. Call Of The Cave Immortal - featuring Xuzhu
5. Cry Of The Water Dragon - featuring Qiao Feng, Duan Yu, and Xuzhu

Book Three : Breaching the Formation 《破阵子》:
Qiao Feng falls from grace after he is revealed to be a Khitan, and is wrongly accused of murdering some fellow martial artists. He becomes an outcast of the martial world of the Han Chinese-dominated Song Empire, which is at war with the Khitan-led Liao Empire.
Qiao Feng leaves to verify the claims that he is a Khitan and investigate the murders. He is accompanied by Azhu, who loves him. He finally accepts the fact that he is indeed a Khitan and assumes his ancestral name "Xiao Feng". In tracking down a mysterious "Leading Big Brother", whom he believes is responsible for the murders and his parents' deaths, he mistakenly thinks that Duan Zhengchun is the "Leading Big Brother", and challenges him to a one-on-one fight. However, it turns into a tragedy when Azhu disguises herself as Duan Zhengchun and allows Xiao Feng to kill her. Duan Zhengchun is actually Azhu's father.
Regretful, Xiao Feng leaves Song territory with Azi, Azhu's younger sister, whom he had promised to take care of. Azi has a strong crush on him but he does not reciprocate. By chance, Xiao Feng encounters the Liao emperor, Yelü Hongji, becomes sworn brothers with him. Yelü Hongji makes Xiao Feng a powerful noble and gives him a large princely estate.