Akira is a young man wrongfully convicted of murder and sentenced to life imprisonment. To escape his sentence, he agrees to enter Igura, a lethal battle game within the ruined city of Toshima, tasked with defeating the crime syndicate leader Il Re. Orphaned as a child, he grew up in Toshima Bunny Orphanage alongside his closest friend, Keisuke. Though later adopted, he felt no connection to his adoptive parents and left after three years to live independently.

His demeanor is naturally cold and detached; he appears indifferent to others and rarely expresses emotion. This emotional distance makes him seem abrasive, leaving even close acquaintances struggling to grasp his thoughts. Yet beneath this exterior lies deep concern for those he cares about, particularly Keisuke, though he seldom shows it openly. A hidden naive or childish facet surfaces under specific circumstances. Physically, he has messy dark grey hair, dark blue or green eyes, and pale skin. He typically wears an orange t-shirt, light grey jeans, white high-top sneakers, and a black bomber jacket with a white fur-trimmed hood.

Before imprisonment, he reigned as the undefeated champion of the street fighting tournament "Bl@ster," competing under the alias "LOST" in the RAY district. This background, combined with lifelong military training, granted him exceptional martial arts and armed combat proficiency. He wields a distinctive dagger acquired in childhood from a mysterious figure named Nano, symbolizing a promise for their future reunion. His combat style relies on precision and agility to dispatch opponents efficiently. Extensive Bl@ster experience endowed him with remarkable stamina and endurance. A unique physiological trait allows his blood to neutralize the drug Line (Rein) for addicts, inducing severe convulsions instead of enhanced strength.

His relationships are complex. His bond with Keisuke is foundational, marked by protectiveness and frustration over Keisuke's self-deprecation and idolization; Akira desires Keisuke to see them as equals. Upon encountering Rin in Toshima, he initially views the boy's cheerfulness with suspicion, sensing underlying darkness, though mutual trust and friendship later develop. Interactions with Igura's most feared fighter, Shiki, begin antagonistically, evolving into a mix of fear and fascination, particularly after Akira's kidnapping by him. Reuniting with Nano triggers recovered childhood memories and a rekindled connection. Conversely, he finds the sadistic tendencies of Vischio manager Arbitro deeply unsettling. He forms reluctant respect for fellow fighter Takeru, admiring his determination to support his family before Takeru's descent into Line-induced madness horrifies him.

Navigating Igura forces him to confront his past and emotions. He witnesses extreme violence, including sexual assault and murder, upon arriving in Toshima. Key events include clashing blades with Shiki, surviving attacks by Line-addicted fighters affected by his blood, and discovering Keisuke’s drastic personality shift after taking Line. A pivotal moment involves recovering suppressed memories of being a childhood test subject in the clandestine "Nicole Experiments." Physical and psychological trials culminate in a confrontation with a Line-addicted Keisuke, who attacks him with screwdrivers; outcomes vary significantly based on his responses, ranging from mutual survival and potential reconciliation to tragic failure and death. Later, he faces the truth behind his murder framing, orchestrated by Emma to manipulate him into Toshima as part of a mission targeting Nano. In the climax, he witnesses Shiki kill Keisuke while Keisuke attempts to protect him—a devastating loss occurring as they flee the collapsing city.