TV-Series
Description
Critter is a minor antagonist who appears during the War of Underworld sub-arc of the Alicization arc. He is a skilled hacker and cyber-criminal, working as a consultant for the cyber operations department of a private military company called Glowgen Defense Systems. His background establishes him as a first-class cyber criminal whose technical expertise makes him a valuable asset for illegal operations. Physically, Critter is depicted as a skinny man with short-cropped blonde hair and pale-grey eyes. His complexion is noticeably pale, and he wears rustic, goggle-like glasses with metallic frames that sit on his scrawny cheeks.

Critter is part of the twelve-member assault team that infiltrates the Ocean Turtle, the Japanese floating facility where the Underworld is hosted. His primary motivation in the story is fulfilling his role within the operation, which is to support the team's leaders, Gabriel Miller and Vassago Casals, by using his hacking abilities to compromise Rath's systems. His personality reveals a somewhat argumentative and impatient side, as shown when he becomes frustrated with his inability to hack the main control console quickly and begins blaming his teammates for taking too long to secure the area. This leads to a heated exchange with Vassago, which is only stopped by Gabriel's intervention.

His role in the story is largely a technical support function for the antagonists. He is the one who operates the system console in the Ocean Turtle's main control room after the Japan Self-Defense Force locks it down. Unable to bypass the lock, he instead accesses the Underworld's visual feed. He explains the structure of the virtual world to his comrades, noting the distinction between the Human Empire and the Dark Territory. When Gabriel and Vassago propose logging into Underworld directly, Critter is instrumental in making this happen. He discovers that the high-ranking administrative accounts for the Human Empire are password-protected, but locates two unsecured "super accounts" in the Dark Territory: a dark knight and Emperor Vecta. These accounts are then taken over by Vassago and Gabriel, respectively.

During this process, Critter also discovers the term "Final Load Test" within the system. Later, as Gabriel and Vassago operate within the virtual world, Critter remains at the console in the real world, acting as a line of communication. He reminds them of their mission objectives and the limitations of their accounts, notably that he cannot reset them if they are killed. Critter escalates his role by orchestrating a beta test that channels thousands of American VR game players into the Dark Territory to bolster its forces. His actions thus directly escalate the scale of the war within the Underworld, moving beyond simple infiltration to a full-scale invasion leveraging real-world players.

Key relationships for Critter are strictly professional, centered on the other members of the Glowgen team. He has a tense dynamic with Vassago Casals, whom he argues with over the failed hack. His ultimate superior is Gabriel Miller, the operation's leader, to whom he reports his progress and takes orders. Other than these interactions, he has no personal ties to the main cast of characters.

Throughout his appearance, Critter's development is minimal as he is a supporting antagonist whose function is to enable the actions of the primary villains. However, his role does evolve from a simple hacker to a more active agent of sabotage. After Gabriel is defeated, Critter acts independently by attempting to rig the Ocean Turtle's main engine with explosives in an act of retaliation. This plan is thwarted by Akihiko Kayaba, the original creator of the Soul Translator technology. After this failure, Critter shifts his focus once more, aiming to abandon the destruction of the facility to instead try and capture Alice's light cube directly from the real world, demonstrating a persistent, goal-oriented nature.

His notable abilities lie entirely in the real world rather than within Underworld itself. Critter possesses no combat skills but is a highly proficient hacker and system operator. His skills allow him to navigate Rath's secure consoles, bypass security protocols to a degree, analyze system functions, and facilitate the large-scale login of thousands of external VR players into the Underworld environment. He is presented as a significant technical threat, even if he is physically unremarkable.
Cast