Yolko (ヨルコ, Yoruko?) is one of the 10,000 players who were trapped in the online game «Sword Art Online». She was a former member of the guild «Golden Apple». She and Caynz team up to find the culprit who killed Griselda.
Yolko is a 17-18 year old girl, with slightly curly, deep-blue hair in-game and has simple large eyes that are of the same colour as her hair. Yolko wears a light blue tunic with a chestguard, knee-length, brown shorts and dark leggings. In her disguise as Griselda's ghost, she wears a cape with a hood, under which she wears a tunic of a darker shade of blue with a chestguard, tight, white leggings and grayish boots and wields an estoc made by Grimlock. In real life, she has brown hair.
Yolko appeared to be a extremely terrified and traumatized person when her former guildmate and boyfriend, Caynz, "died", but she is proven to be a good actor when it is revealed that she and Caynz had staged the murder and Yolko had pretended to have been traumatized.
However, Yolko is not a person who likes to take advantage of people, as she did leave herself on Asuna's friend list, despite it being an obvious way to find out about their trick, likely to atone for her lies and to show that she trusted Asuna, and, at Griselda's grave, she claimed that she was going to properly apologise for doing so after the matter had been resolved.
Yolko is also a person who seeks justice, as proven by how she and Caynz staged their own murders to find out the truth behind Griselda's murder.
She was part of a small guild called Golden Apple, which only had eight members and among them was her boyfriend, Caynz. One day, the group found a rare-drop item and they voted to decide what to do with it, Caynz was in favor of keeping the item, so she also voted in favor of keeping it, but after losing in the voting three to five, they decided to sell the ring. The guild leader, Griselda departed up the front lines to sell the ring but never came back, only to discover that she was dead. The guild was disbanded but the culprit was never found.
While Kirito and Asuna are having dinner, she screamed seeing Caynz hanging from the church's window, later she explained that she was going to eat with Caynz but then got separated. She stays in an Inn while Kirito and Asuna investigate, later she talks to Schmitt, and starts to have a panic attack before being stabbed in the back by the mysterious murderer that also killed Caynz. She is later seen alive with Caynz at the gravesite of Griselda, confronting Schmitt about Griselda's death. After being saved by an ambush by PoH and two other Laughing Coffin members, with the help of Kirito and Asuna, they soon found out who was responsible for Griselda's death, as it was none other than her own husband, Grimlock who helped them carry out their schemes against Schmitt. After Grimlock admits his crimes, Yolko thanks Kirito and Asuna for solving the case and accompanies Schmitt and Caynz to take their former friend to prison.Dicey Cafe, along with the other SAO survivors.