Akira Natsume was a shy 2014 high school student with a fearful yet skilled relationship with technology. His life ended when a truck struck him during an attempt to stop harassment; his brain was preserved. Sixteen years later in 2030, he awakened as the cybernetic weapon EX-ARM No. 00. Disoriented and amnesiac, he discovered his mind could interface with electronics, granting abilities like city-wide camera surveillance, network hacking, and direct control of android bodies like his police partner Alma for combat. His disembodied state physically manifested as an inability to close his mouth. Working with the police's EX-ARM Countermeasure Division, especially Minami Uenozono and Alma, his goals shifted from recovering memories and regaining a body to actively protecting others. This resolve stemmed from regret over failing to save the woman during the harassment incident and his brother Shuichi's encouragement to be brave. He battled adversaries wielding other EX-ARM units, including his antagonistic counterpart Beta (EX-ARM 00-b), who shared his appearance and caused a catastrophic Tokyo attack. His character arc involved grappling with existential isolation and dehumanization, often being called "00," and longing for normalcy despite his powers. Key developments included uncovering Shuichi's role in EX-ARM research and Beta's creation, and confronting ethical power-use dilemmas. In the climax, he sacrificed himself by detonating EMP devices above Japan to neutralize Beta's rogue AI network, destroying his brain unit and disabling all nationwide technology, prioritizing humanity's safety over his existence. Across all media, including the manga sequels *EX-ARM EXA* and *Ex-Arm Another Code*, his story consistently centered on identity, redemption, and the consequences of merging human consciousness with weaponized technology.