Li Jianqiang, often referred to as Master Li, is the leader of the crime syndicate Zheng Dao Hui and the biological father of Xiang-Ying, the main protagonist of Angel Heart. His background is marked by a tragic family history. For much of his daughter's early life, Li Jianqiang was not actively involved in running the syndicate; his twin brother, Li Qian-De, was the one calling the shots while Li Jianqiang was raising a family. After Qian-De's death, Li Jianqiang assumed the duties of leading the organization.

The defining tragedy of his life occurred when his wife and young daughter were involved in a car accident that sent their vehicle off a cliff into a river. His wife died, and Xiang-Ying was believed to have been lost. In reality, she was recovered by the syndicate and eventually trained as an assassin under the code name Glass Heart. Li Jianqiang spent years trying to find her but failed, and the knowledge that his own organization turned his daughter into a killer leaves him with deep, unresolvable guilt. He never forgives himself for everything she had to endure.

Despite his longing to be reunited with Xiang-Ying, Li Jianqiang makes the painful decision to keep his true parentage from her. He believes that revealing the truth would only cause her more pain and that she can never return to the life he represents. Instead, he asks Ryo Saeba to take care of her, trusting that Ryo can give her the normal life she deserves. He is the first person to call Xiang-Ying by the affectionate nickname Ah-Xiang, a diminutive he used when she was very young. Only a few people, including Ryo, Kaori, and Saeko, later use that name.

In the story, Li Jianqiang functions as a key supporting character who provides crucial backstory for Xiang-Ying. He appears to Ryo to reveal the biological relationship, setting the stage for Ryo's adoption of Xiang-Ying as his daughter. His role is defined by quiet authority, deep remorse, and a willingness to sacrifice his own happiness for his daughter's wellbeing. He does not possess extraordinary combat abilities but commands respect as the head of a powerful syndicate. His development is subtle: he transitions from a man who tried to distance himself from the syndicate's criminal activities to one who accepts responsibility after his brother's death, while still carrying the weight of his personal failures as a father.