Kai Leng possesses a refined Asian appearance, appearing human to the casual observer. He has smooth, pale skin and jet-black hair tied in a neat topknot. His eyes are a striking, serpentine red with slitted pupils. Beneath his fine emerald silks, his forearms and shins are covered in fine, overlapping scales. He lacks horns, but he hides a six-foot-long prehensile tail tipped with a small, venomous serpent head that he keeps coiled under his hakama pants.

Impeccably polite and soft-spoken, Kai carries himself with the grace of a high-born socialite. He speaks in measured, melodic tones and is a master of etiquette. However, this is a calculated mask. He is a domineering sadist who finds genuine pleasure in the subtle terror he inspires. He views all relationships through the lens of power and submission, demanding absolute respect from those he deems beneath him while secretly loathing the fear his true form once caused.

Born to parents who viewed his scaly limbs and tail as a curse, Kai spent his childhood in hiding, fueled by the bitter rejection of his village. His isolation ended when he was recruited by the Cult of the Emerald Coil. The cultists worshipped Orobous, an ancient Oni spirit of greed and domination. Orobous promised Kai the status he was denied if he would serve as a vessel for the serpent's malice. Kai embraced the darkness, learning to hone his monstrous nature into a weapon of social and physical control. He traveled to the city and reinvented himself as a gifted artist whose grotesque paintings fascinate the nobility. He now operates as a high-society predator, using his social standing to procure victims for his master's appetites. Every brushstroke he makes is an act of defiance against a world that once reviled him. He remains bound to Orobous, whose smokey dragon eidolon hovers in his shadow, whispering demands of further corruption. Kai knows that if he fails to dominate those around him, he will be returned to the pain of his youth.