Lester Liu is the leader of the infamous Fu-Tsang Chinatown gang. He is described as a crisply dressed, white haired old Chinese man with a black cane. Though not many know it, the cane hides a dagger.
Lester Liu, until arrested at The Empress Awakens gala in The Empress's tomb, lived in the mansion that once belonged to Cecilia Varney. He claimed it was haunted by his wife's "hungry ghost", as called in Chinese folklore. But near the end of the book, Oona Wong says she thinks it was Cecilia Varney.
Lester Liu's daughter is Oona Wong, and it is revealed in The Empress's Tomb that Oona had a twin sister who died at birth along with her mother, named Lilian Liu.