Afasys

Afasys (アファシス), alternatively spelled as ArFA-Sys in Western localisations, is an original Sword Art Online game character and the Protagonist's personal companion in Sword Art Online: Fatal Bullet. Afasys is a rare type, modeled Type-X, of an Artificial Intelligence (AI) companion called the Artificial Financial Adviser System and her full ID is Afa System Type-X A290-00. Due to Afasys only allowing the Protagonist to use Afasys's official name, the companion was nicknamed as Rei (零) by Leafa in reference to the zeros appended to her Unit ID.

Gun Gale Online
Both female (canon) and male (alternative) versions of Afasys feature white and purple prominently as their canon looks. They both have purple eyes, white hair and a skin-tight, purple-on-white suit. While the female Afasys has short and straight hair, the male Afasys variant has short and messy hair.

Personality
As a Type-X Unit, Afasys features a distinct personality, unlike the other models. Afasys is a clumsy companion who tends to make simple mistakes while handling a task, and is very forgetful in terms of remembering key information. As an AI companion, their battle personality can be adjusted by the Protagonist to suit their needs based on various parameters. While Afasys' core personality traits are predetermined, how they express themselves can also be adjusted by the Protagonist to sound bright, stoic, cute, zealous, or serious.

With the addition of the first DLC, Champion of Gunfire, situational emotes have been added as adjustable parameters that allow Protagonist to decide how Afasys reacts to certain events, such as waving when the Protagonist meets a friend, or pumping their fist up in the air upon leveling up.

Fatal Bullet
Afasys was implemented into Gun Gale Online (GGO) as part of the Gold Rush update via a special tournament. During the event, they registered the Protagonist as their master when the player touched their stasis capsule device while examining it. Having emerged from the pod, Afasys hesitantly addressed the Protagonist as their master as Kirito charged at the latter, prompting the Photon Sword Wielder to halt his attack. After the trio were joined by Kirito's ally Asuna and the Protagonist's friend Kureha, the android focused on completing their main system check and startup processes while reiterating their registration to the Protagonist when Kureha attempted to claim ownership over them, although they acknowledged the girl as their master's superior.

Once their main system startup was finished, Afasys gifted the Protagonist with an Ultimate Fiber Gun (UFG), an experimental grappling device that was relatively easy to utilize. Having taught the Protagonist how to use the UFG, the duo and Kureha were automatically transported to SBC Glocken at the tournament's conclusion, where Afasys followed their master to a party held by Kirito's friends to become better acquainted with each other.

After the party, Afasys explained to the Protagonist their purpose as an Artificial Financial Adviser System, though their related skills and stats were low-level on accord of their master being a beginner player. In order to strengthen themselves, the pair joined Kureha and Kirito on a tour of SBC Glocken, learning how to use the various facilities therein to prepare themselves for their expeditions into the field. During the tour, they met several of Kirito's friends that were not present at the party, as well as a gruff gunman named Bazalt Joe who saved them from being conned by a merchant player. While doing their own exploration of the city sometime later, Afasys got separated from the Protagonist, only managing to reunite with them thanks to aid from Daisy, another Type-X ArFA-Sys Unit, and her mysterious master Zeliska. Shortly afterwards, Afasys revealed to Kureha and the Protagonist that some of their functionalities were incomplete due to missing a few parts; recovering these components would restore the android's abilities and enable them to unlock the SBC Flügel, a new area to be implemented as part of the Gold Rush Update.