Olivia is a 38-year-old Chinese American commercial photographer living in San Francisco. She grew up in Daly City and struggles with a fragmented sense of cultural identity, often feeling embarrassed by her half-sister's traditions. She approaches the world through a rational, skeptical lens, actively rejecting the supernatural claims her sister makes. She is currently undergoing a separation from her husband of 17 years.

Kwan is Olivia's older half-sister, born in China to Jack Yee's first wife. She works at a drugstore and possesses a boisterous, unfiltered joy that often makes her American relatives uncomfortable. Kwan claims to have "yin eyes," an ability that allows her to see and speak with ghosts. She remains intensely devoted to Olivia despite facing childhood rejection and involuntary psychiatric treatments.

Simon is Olivia's husband, an archaeologist and public relations writer. He struggles to let go of his past, frequently speaking of his deceased former girlfriend in the present tense and preserving her belongings. This unresolved grief creates a permanent emotional barrier in his marriage to Olivia. He discovers early in his adult life that he is sterile.

Louise is Olivia's mother. She sponsors Kwan's immigration to the US out of a desire to be unconventional, but she provides inconsistent maternal care to her children. Her flightiness and emotional neglect create a void in Olivia's childhood, prompting Kwan to step in as a surrogate caretaker.

Miss Banner is an American missionary living in 19th-century China during the Taiping Rebellion. She resides at the Ghost Merchant's House in the village of Changmian. Initially arriving with intentions to civilize the local population, she finds herself transformed by her environment and deeply dependent on her local companion.

General Cape is an American mercenary operating in China during the Taiping Rebellion. He speaks fluent Chinese dialects and possesses a charismatic presence that inspires local villagers to join the rebellion. His ambitions drive him to switch allegiances between the rebels and the Qing government.

Jack is the father of Olivia and Kwan. He immigrated to the United States from China, leaving behind his first wife and daughter. On his deathbed, he reveals Kwan's existence, insisting that the ghost of his first wife demands he bring their daughter to America.

Elza is Simon's deceased former girlfriend who died in a skiing avalanche in Utah. She becomes posthumously famous for her music. Her lingering memory and the unresolved circumstances of her death cast a long shadow over Simon's subsequent marriage.

Nunumu is a one-eyed Hakka girl living in 1864, whom Kwan claims as her own past-life identity. After rescuing an American missionary, she moves to the village of Changmian and serves as her loyal companion amidst the violence of the civil war.

Bob is Louise's second husband and Olivia's stepfather. He provides the family with a stable suburban life in Daly City, though his surname carries an unexpected history that Olivia discovers later in life.

Kevin is Olivia's brother. He grows up in the same suburban environment and shares information with Olivia regarding the origins of their stepfather's surname.

Tommy is Olivia's brother, raised by Louise and Bob in the United States. He represents the normative American family structure that Kwan disrupts upon her arrival.

George is Kwan's husband in San Francisco. He provides a stabilizing, supportive presence for Kwan's eccentricities and maintains a friendly relationship with Olivia and Simon.

Yiban is a half-Chinese translator working for General Cape during the Taiping Rebellion. His history of abandonment and servitude binds him to Cape, though he struggles with divided loyalties when he falls in love.

Lao Lu is a boatman in 19th-century China who later becomes one of Kwan's guiding spirits. In the past, he resides at the mission in Changmian and helps secure food during times of starvation.

Li Bin-bin, known as Big Ma, is Kwan's great-aunt residing in China. She holds the secrets regarding Jack Yee's stolen identity. Kwan deeply desires an apology from her for past grievances.

Du Lili is Kwan's old friend in China. She acts as a host to the American travelers, preparing traditional meals and organizing village customs. She suffered a severe mental health crisis following the death of her adopted daughter.

Pastor Amen is a missionary working alongside Miss Banner in 19th-century China. He attempts to convert the local Hakka population through rigid religious instruction, unaware that his messages are being creatively mistranslated.

Mrs. Amen is the wife of Pastor Amen and a fellow missionary in Changmian. She assists in the daily operations of the mission during the Taiping Rebellion.

Zeng is a local peddler in 19th-century China who falls in love with Nunumu. He offers to help her escape the violence of the approaching soldiers.

Buncake is Kwan's childhood best friend in China. Unable to speak, she communicates closely with Kwan until they are both involved in a tragic drowning incident during a flood.

Toby is a deceased friend of Kwan who acts as her spiritual intermediary. Kwan relies on his spirit to help communicate with other entities in the Yin World.