Benny is a teenage boy of mixed Japanese and Korean descent living in San Francisco. Following the loss of his father, he begins hearing the voices of inanimate objects, starting with his father's ashes and escalating to everyday items like scissors and windows. He struggles in school and experiences severe social isolation as the constant noise of objects grows increasingly overwhelming. Seeking a quiet refuge, he regularly skips school to hide in the public library.

Annabelle is Benny's mother, a middle-aged woman who works for a news-monitoring agency. She uses consumerism and accumulating objects to cope with her overwhelming anxiety about providing for her son. Her growing collections create severe physical clutter in her home, which heavily distresses Benny. She holds tightly to the memory of her husband and finds temporary comfort in reading a book on Zen Buddhism.

The Book is a semi-living, collaborative entity acting as the narrator of Benny's life. It possesses a collective consciousness shared with all other books and frequently addresses Benny directly. The Book desires to experience human emotion and physical sensation by chronicling the events of Benny's adolescence.

Kenji is Benny's late father and Annabelle's husband. A jazz musician of Japanese and Korean descent, he previously spent time as a Zen Buddhist monk. Though he dies just before the novel's main events, his presence lingers through his cremated ashes, the memories he leaves behind, and the rearranged word magnets on the family refrigerator.

Alice is an older teenage girl and artist who uses the alias the Aleph. She frequently spends time at the public library and creates public art projects, including distributing slips of paper with strange instructions and crafting snow globes depicting environmental disasters. She lives on the margins of society and helps Benny understand his unusual experiences.

Slavoj is a houseless poet originally from Slovenia who lives in San Francisco. He uses a wheelchair and openly admits to hearing voices, which he channels into an ongoing epic poem titled Earth. He spends much of his time at the public library or in an abandoned warehouse, offering philosophical lectures to those around him.

Aikon is a Zen Buddhist monk living in Japan. Before joining the monastery, she worked a high-stress corporate job at a fashion magazine, which she abandoned after a crow stole her expensive tiara. She writes a book to promote mindfulness and simplicity, inadvertently building a large following of readers seeking relief from their material attachments.

Dr. Melanie is a child psychiatrist who treats Benny after he experiences a crisis at school. She approaches her job with clinical professionalism but struggles to find the time to properly meditate or write in-depth evaluations. She attempts to understand Benny's condition while prescribing medications to manage his symptoms.

Cory is a librarian at the public library in San Francisco. She knows Benny from his childhood visits and observes his and Annabelle's lives from a distance. She maintains an awareness of the library patrons and steps in to offer practical support when people are in distress.

Mrs. Wong is the landlady of the property where Annabelle and Benny reside. She lives nearby and expects the property to be kept clean. After suffering a severe fall, she is hospitalized and transfers her landlord duties to her son.

No-Good is the nickname Annabelle and Benny use for Mrs. Wong's son. He takes over the management of the rental property while his mother is hospitalized. He is heavily critical of Annabelle's hoarding habits and threatens eviction if the property is not cleared of garbage.

Mackson is an older teenager who shares a room with Benny in the hospital. He is quiet and keeps to himself early on, but he maintains a connection with Alice and helps run a peer support group for young adults dealing with mental health challenges.

Jevaun is a security guard at the public library in San Francisco. He monitors the building after hours and is responsible for patrolling restricted areas like the Bindery. He assists Cory when incidents occur on the library grounds.

Kimi is Aikon's assistant at the temple. She helps manage correspondence and discusses the emails they receive from readers. She shares Aikon's cultural perspective on spirits and objects.

TAZ is Alice's pet ferret. He lives with her in the abandoned warehouse and accompanies her during her visits to the public library.

Jake is a resident of a homeless encampment in a small park near Benny's neighborhood. He shares food with Benny when the teenager wanders into the park after an argument with Annabelle.

Dozer is an individual living at the homeless encampment in the park. He helps calm the camp's dogs when Benny arrives.

Terence is an unhoused individual living in the homeless encampment. He is part of the group that invites Benny to share their canned rice and beans.

Joe is a mediocre jazz musician and Annabelle's former boyfriend from her time in library school. His behavior at a jazz club inadvertently leads to Annabelle meeting Kenji.

Ms. Pauley is Benny's teacher. She is present when Benny is overwhelmed by the voices of a pair of scissors during a classroom activity.