In SAO, Silica became the first player to tame a Feathery Dragon, which she named Pina (the same name as her cat in the real world), despite SAO being the first VRMMO she's ever played. She is introduced as a character whose parties treat her as a mascot and is immensely popular on the middle Floors due to her pet and her status as one of the rare Beast Tamers. She eventually becomes arrogant, which leads to her separating from her party in the middle of a hunt and getting lost in the forest. Soon after, a fight at the forest was the cause of Pina's death and almost hers before she was saved by Kirito, who then helps her revive the dragon. She is in the youngest age group of SAO players that are still active. She usually stays away from the males, who try to marry her despite the fact that she is only 13.
After a dispute with Rosalia, Silica leaves the party in the middle of their hunt. She goes through the forest alone and is attacked by multiple «Drunken Apes». Her familiar, Pina takes a hit for Silica and dies but she is saved by Kirito as she resembled his sister. Kirito tells her about a way to resurrect Pina. Though it is outside her level range she resolves to go one day, but finds out she only has three days to do so. Kirito agrees to help her get there, so they set off and return to town. They end up staying in an inn in order to discuss their plans to retrieve the flower.
The next day, she sets off with Kirito to find the flower. Despite encountering a few monsters, they reach their goal but on their way back they're ambushed by Rosalia and members of the «Titan's Hand» guild. Kirito reveals his real motive, sending the Titan's Hand guild to prison, and dispatches them easily. They finally agree to meet again, but in the real world. In the process of getting the flower, she gained feelings for him, but once she realized his skills, she realized that they could never be together in the game and begins to see him as a big brother figure, but continues to have feelings for him. Later on it is revealed that Pina was revived.
After Asuna is rescued, Silica and Lisbeth make a pact that they will give Kirito and Asuna one month together without interfering before they make their individual moves on him, however they quickly regret it. She joins Kirito and his friends in ALO right after they meet in the real world and they often go together in quests. She plays ALO as a Cait Sith beast-tamer along with her partner Pina.
With her avatar in SAO, she reminded Kirito of his sister, Kirigaya Suguha.
In the Blu-ray/DVD package volume 2, character song CD will feature Silica (Hidaka Rina) singing "☆Lovely Super Idol☆" as the 3rd Character Song in this series. This CD is bundled along with the 2nd Song, which is sung by Sachi (Saori Hayami)
Even though «Sword Art Online» is advisable for gamers above age 13, Silica started playing the game when she was 12 years old.
Keiko's family follows a tradition when naming their children. Since Keiko's grandfather was a chemist, he named his son Tetsuhiko after iron (tetsu in Japanese) since Tetsuhiko was born on the 6th of February and the 26th element (2nd month and 6th day) in the periodic table is iron. Tetsuhiko continued this tradition and named his daughter Keiko after the 14th element, silicon (keiso in Japanese), as Keiko was born on the 4th of October but Tetsuhiko couldn't make a girl's name after the 104th element, Rutherfordium, so he resorted to merging 10 and 4 to get 14.
Keiko's display name, Silica, means Silicon Dioxide (SiO2). She chose this name for her character due to her real name being based on silicon, the 14th element in the periodic table. The reason why she chose "Silica" instead of "Silico" was because "Silica" sounded cuter. She even ties her hair with two red ribbons to have 12 ring baubles which symbolize 2 oxygen atoms bound to her.