Komura is a 31-year-old salesman in Tokyo who caters to wealthy clients looking to purchase luxury electronics. He lives a comfortable, unexamined life and considers his routine marriage to be secure, shielding him from deeper existential worries. When his wife abruptly abandons him, she leaves a note calling him an empty "chunk of air," exposing his emotional detachment from both her distress and the world at large.

Junko is a runaway teenager from Tokorozawa who now works at a convenience store. She lives with her surfer boyfriend but finds more solace in classic literature and watching driftwood fires burn on the beach. She struggles with intense feelings of emptiness and alienation stemming from her difficult home life.

Miyake is a middle-aged artist and eccentric loner living in the quiet coastal town of Ibaraki. He left a wife and two children behind in Kobe years ago. He expertly builds bonfires that offer warmth and comfort to those who watch them, using his art to express his inner fears and regrets.

Yoshiya is a 25-year-old man living in Tokyo with his highly eccentric, religious mother. Raised to believe he is the literal son of God, he struggles with his independence and an overwhelming desire to uncover his biological parentage. He frequently uses alcohol to cope with the stress of acting as a caretaker for his parent.

Satsuki is an accomplished pathologist in her fifties who specializes in the immune system and the thyroid. Following a painful divorce and a relocation from Detroit to Tokyo, she carries a deep, hardened resentment toward a man from her past. She finds temporary reprieve from her stress by swimming alone in isolated pools.

Katagiri is a 40-year-old loan collection officer in Tokyo. He lives a solitary, thankless life managing difficult accounts for his bank and financially supporting ungrateful siblings. Despite his low self-esteem and unremarkable physical appearance, his quiet endurance and lack of complaint catch the attention of an unusual ally.

Frog is a giant, polite, talking amphibian who appears in Tokyo to prevent an impending earthquake. He is highly articulate, enjoys quoting classic literature and philosophy, and respects Katagiri for his bravery and uncelebrated hard work at the bank.

Worm is a dormant, gigantic creature living deep beneath Tokyo. Awakened by the recent Kobe earthquake, it continuously absorbs the resentment and hatred of humanity. Its physical movements below the surface threaten to cause a catastrophic seismic event that will destroy the city.

Junpei is a 36-year-old short story writer known for his tales of unrequited love. He forms one-third of a tight-knit college trio alongside Sayoko and Takatsuki. Often passive in his personal life, he hides his deep affection for Sayoko while acting as a dependable, constant fixture in her broken family's life.

Sayoko is an educated woman who met her two best friends in a university literature department. After a divorce, she works steadily translating Junpei's short stories and raises her young daughter. She maintains a profound emotional reliance on Junpei's steady, comforting presence in her life.

Sasaki is a coworker of Komura at the electronics store in Tokyo. Upon learning about Komura's sudden divorce and time off, he seizes the opportunity to ask him to hand-deliver a small, mysterious box to his sister in Hokkaido.

Keiko is Sasaki's sister, a young woman living in the freezing northern city of Kushiro. She retrieves the small cremation-style box sent by her brother and introduces the visiting Tokyo salesman to local hospitality.

Shimao is a young woman in her mid-twenties who drives a battered car through the icy roads of Kushiro. She acts as an enigmatic guide for the visiting Komura, sharing strange local stories about bears and UFOs while openly discussing the unpredictability of human existence.

Keisuke is a surfer and failing college student who rejected his family's expectations to take over their sweetshop in Mito. He lives in Ibaraki with his teenage girlfriend Junko and prioritizes living carelessly in the present moment over dwelling on the past.

Miss Osaki is Yoshiya's eccentric, devoutly religious mother. She became a staunch believer after a suicide attempt in her youth and raised her son to believe his father is God. Prone to extreme behaviors, she relies heavily on Yoshiya to maintain stability in her daily life.

Mr. Tabata is a devout man who intervened in Miss Osaki's life during a crisis, saving her and introducing her to his religion. He served as a strict spiritual authority figure during Yoshiya's childhood, teaching him not to test God.

Nimit is a Thai man in his early sixties who works as a chauffeur and local guide. Having served a Norwegian businessman for over three decades, he developed a profound sense of loyalty and a deep love for old jazz music. He quietly intuits that his new client carries a heavy emotional burden.

Takatsuki is a charismatic, athletic reporter who befriends the bookish Junpei in college. He acts decisively in his personal life, openly pursuing Sayoko and marrying her before their eventual divorce. He relies heavily on Junpei to smooth over his family issues and mediate custody visits.

Sala is Sayoko and Takatsuki's four-year-old daughter. Deeply traumatized by continuous television coverage of the Kobe earthquake, she suffers from severe night terrors. She finds immediate solace in the gentle, creative animal fables Junpei invents for her.