Bai-Luan is the elderly and ruthless leader of the Ming Chinese contingent that serves as the primary antagonistic force in the story. He is a high-ranking agent acting directly on the orders of the Ming Emperor, dispatched to Japan with a specific and dire mission. This mission is to capture a young boy named Kotaro, whose blood is a crucial component for a ritual intended to create a potent elixir known as Xian medicine, a substance prophesied to grant immortality.

In terms of appearance, Bai-Luan is depicted as a very old man, marked by his age and a blind left eye. Despite his frail appearance, he commands absolute authority over the group of skilled Chinese warriors, including the formidable Western swordsman Luo-Lang, whom he sees as a mere tool to achieve his goals. His personality is defined by a cold, calculating, and unfeeling nature. He is thoroughly bloodthirsty and pragmatic, showing no hesitation to sacrifice others for his own benefit or the completion of his mission. A core aspect of his motivation is a deep-seated, selfish desire for immortality. While he is completely loyal to the Ming Emperor, he is also driven by the personal goal of using some of the medicine to extend his own life, as he states that the older one gets, the more one clings to life.

In the story, Bai-Luan's role is to oversee the construction of a large ritual altar on the lands of Lord Akaike, an arrangement secured by the promise of gold. He relentlessly pursues Kotaro, sending his warriors to retrieve the boy so the immortality ritual can be completed. His key relationships are purely hierarchical and transactional. He views his subordinates, including Luo-Lang, as disposable assets. This dynamic is exemplified when he attempts to shoot the ronin Nanashi with his flintlock pistol, an act that is only stopped by Luo-Lang, who wants to face the swordsman in a fair duel. Bai-Luan is also shown to criticize Lord Akaike's samurai when they turn against him, further highlighting his position as a commander who expects absolute obedience.

Bai-Luan does not undergo significant personal development or redemption; his character remains a steadfast obstacle defined by his cruelty and ambition. His notable abilities lie not in direct combat, but in his strategic command and his ruthless use of weaponry, specifically a flintlock gun, which he uses to shoot Itadori, demonstrating his preference for efficient, unceremonious killing over the code of honor followed by the swordsmen around him.