Silica is the avatar name of Ayano Keiko, one of the many players trapped in the game Sword Art Online. Her class is Beast Tamer, which allows her to control and summon a pet to aid her in combat. At the young age of 12, she is one of the youngest players of Sword Art Online. However, she is able to hold her own in combat and solo monsters easily with her Feathered Dragon, Pina. Her weapon of choice is a dagger.

In the anime, she is popular among parties for her cute looks and status as one of the only Beast Tamers in the game. Because of this, many people bring her along as a mascot for their party. She gets frustrated from this and wanders off on her own. Her arrogance leads to the death of Pina and nearly her own, but she is rescued by a passing Kirito. She joins Kirito on a quest through the Hill of Memories which, upon completion, grants her an item with the ability to revive Pina. She feels like is too weak for Kirito so she resolves to strengthen herself while Kirito continues to the frontlines.

Silica and Pina are an inseparable bond. Despite being an AI character, Pina shows close attachment to Silica, taking a fatal blow to save Silica's life. The blue Feathered Dragon boasts healing and support abilities, but can also hold its own in combat. Combined with Silica's offensive powers, the two can solo content that would otherwise be difficult for others.

Silica is quite naive because of her young age. She is quick to jump to conclusions, leading her to get embarrassed very easily and make rash decisions. But she is able to quickly recognize her mistakes and is apologetic to those she causes troubles for. Sometimes she apologizes too much but in the end, she resolves to better herself so she doesn't have to lean on people so much.

After her time in Sword Art Online, she continues playing online games such as Alfheim Online. She joins Kirito as a Cait Sith in the latter game. She cheers him on with the other girls as Kirito competes in the Bullet of Bullets competition in Gun Gale Online. She also joins him to retrieve the mythical sword Excalibur in Alfheim Online.