Yin Hai is a commander in the Zhao Military and Mu Li's bodyguard.

Yin Hai is a slim, young and beautiful woman. She has long dark hair tied at the back and wears a robe with armor around her torso. Unlike other army commanders, she doesn't wear any kind of armor protection on her head.

STATS:
Strength 84
Leadership 85
Knowledge 82
Capable dual wield swordsman

When low-born servant boys Piao and Xin set out to become the world’s greatest war generals, they quickly find themselves caught up in a violent struggle between two noblemen plotting to overthrow the King. After Piao is killed protecting the rightful ruler of the kingdom of Qin, Xin sets out on a campaign for revenge that leads him straight into the fire of war. 
 
Now, with a target on his back and an army of enemies standing in his way, it will be up to a boy with no name and a young king without a throne to return order to their war-torn country in this historical action-drama based on the Tezuka Award-winning manga, Kingdom. 
 
(Source: Funimation) 
 
Note: The first episode aired with a runtime of 50 minutes as opposed to the standard 25 minute runtime.

Millions of years have passed since the times of legends, when the worlds of man and gods were still the same. In these times it was the desires of man that moved the world. It is the period of the 500 year war: the Era of Warring States. Kingdom is the story of a young boy who grew into a great general and all the trials and bloodshed that led him there.


Side stories included in the "Kingdom: Highlights" books:
 
Volume 1: 
1. Kongou (金剛) 
2. Umazakehei Sanbyaku (馬酒兵三百)
 
Volume 2: 
3. Li Mu(李牧): 
An insight to the past of Li Mu and Hai Yin as they resist the forces of the Xion Nus. 
4. Meng Wu and Chu Zi (蒙武と楚子)