Mari is a 19-year-old college student studying Chinese. Feeling overshadowed by her beautiful older sister, Mari struggles with an inferiority complex and often avoids her family. She dresses somewhat boyishly in a parka and a Boston Red Sox hat. Uncomfortable with her sister's sudden, unnatural coma, Mari chooses to spend the night wandering Tokyo's amusement district rather than sleep at home.

Takahashi is a tall, disheveled college student studying pre-law who plays the trombone in a jazz band. He bears a distinct scar on his cheek and a deformed earlobe from a childhood bicycle accident. Raised in a turbulent household after his mother died and his father went to prison, Takahashi feels a lingering sense of being an orphan. He is highly observant, talkative, and takes an active interest in getting to know Mari.

Eri is Mari's 21-year-old sister, a sociology student and former model. She has fallen into an unnaturally deep, voluntary sleep for two months. Her bedroom lacks personal touches, reflecting a lifelong struggle with her identity due to being treated primarily as a beautiful object by society. She exists in a surreal room inside a television screen, entirely cut off from the waking world.

Shirakawa is an outwardly ordinary salaryman working late hours at a software company called Veritech. He dresses in a standard grey trench coat and tries to balance his intense work schedule with a wife at home. Beneath this respectable exterior, he harbors violent compulsions that manifest in the city's love hotels.

Kaoru is the manager of the Alphaville love hotel. Built like a barn with strikingly blonde hair, she is a former professional wrestler whose career ended after a severe back injury. Kaoru acts as a protective, grounding presence in the nighttime city, demonstrating immense loyalty and fearlessness when handling dangerous situations involving her patrons.

Korogi is a maid working the night shift at the Alphaville love hotel. She speaks with a Kansai accent and operates under a pseudonym, meaning 'cricket,' to hide from dangerous individuals in her past. The love hotel offers her necessary anonymity and safety.

An enigmatic figure who watches Eri from within the television screen. He wears a worn brown suit and a tight-fitting mask that completely obscures his features. He sits motionless in a sterile office environment, acting as a silent, anonymous observer.

Guo is a 19-year-old Chinese sex worker operating in Tokyo's entertainment district. She speaks no Japanese and relies on Mari's translation skills after being violently assaulted and robbed by a client.

Komugi is an employee at the Alphaville love hotel with dyed red hair. She works the night shift alongside Korogi and provides practical support when crises arise during their shift.

An intimidating man who rides a black motorcycle. He operates within the organized crime rings of Tokyo's entertainment district and is summoned to handle the aftermath of Guo's assault.