Hosaka Carina Tomo

Argo (アルゴ) is one of the 10,000 players who were trapped in «Sword Art Online» and a beta tester who sells information between players. Kirito often looks to her for her skills.

Appearance
Argo has brown eyes and hair. She wears a hooded cloak. She also has whiskers on her face, which were originally a mark from a quest but now a makeup of her choice.

Personality
Argo is a completely business focused person, with people saying she would sell her grandmother for col. Despite that, she has been known to honor her debts, as was the case with Kirito, saving her from the ninja clan. She is so focused in completing her field guides  that sometimes gets herself into troubles.

It's later discovered by Kirito and Asuna that she is afraid of dogs.

Background
Argo is first introduced as the beta tester who serves a middleman between Kirito and a prospect buyer of his «Anneal Blade +6». She was later revealed to have anonymously  assisted players by creating the guide book, «Strategy Guide by Area», a pamphlet freely distributed in NPC shops. Inside are hunting locations and other resourceful information pertaining to staying alive in the game.

She is willing to sell any information except names of SAO beta testers. She also serves as a middle-man of player dealings.

Argo's whiskers were originally a mark written on her face when she tried to complete the quest that awards the "Martial Arts" extra skill. Unable to complete the quest, the mark remained on her face throughout the entire «SAO Closed Beta». She reapplies a similar makeup on the official server service.

Aria In The Starless Night
Argo had promised Kirito, for the trouble she had caused him (involving her information guide on the First Floor Boss having been incorrect due to changes before the official release, causing the death of the Raid leader, Diabel, and him taking the blame for the circumstances) that she would disclose any information with him for free. He had asked for the reason behind her wiskers. Later, when Kirito opened the gate to the second floor, he noticed Argo running away from two players. He ran after them, using his Tracking Skill to stay close behind. After catching up, he realized that the two players were dressed in a ninja-esque outfit. They were asking Argo about a quest on the 2nd floor that she refused to sell.

At this time, Kirito revealed himself, jumping inbetween Argo and the 2 Players. The two eventually ran away after realizing a large cow mob behind them, that chased after them for some distance. Argo thanked Kirito for helping her, and said that rather than telling Kirito about why she wears the make-up, she will show him, which will also show Kirito the quest that the 2 "ninja" wished to have. After promising he would not hold a grudge against her, Argo showed him the quest NPC, and he accepted the quest given, which was to break a rock that was near unbreakable. However he could not quit the quest, as doing so prompted the NPC to mark his face with wisker-like markings. He realized that this was why she kept the markings, even after the Beta test period, as it had become a part of her. He eventually broke the rock after 3 day and nights.

Red Nosed Reindeer
She later provided information on the approximate location of Nicholas the Renegade, the Christmas boss, to Kirito.

The Day Before
While investigating newly appearing quests of a mysterious nature, Argo picks up a quest on the 22nd floor. A key character in the quest was a dog, which Argo has problems with, so she out-runs the dog, and proceeds to the house which acted as her destination. The house is then pulled up by a tornado, and is suspended near the top of floor. She is trapped there for 2 days, before Kirito and Asuna come by looking for the house she was trapped in. Asuna is the first to become aware of the house floating above the ground, and Kirito realizes that someone is waving their hand out the house. They are unable to determine if the person is a Player, or NPC, until Argo tosses out a used healing potion, which indicated that the person trapped above was a player.

Deciding to help who ever was trapped above, Kirito and Asuna attempt to reach the point that was directly beneath  the house. They came upon a tall tree, that they could probably climb to the top, and attempt communication, but before that, a dog appeared, which Asuna picked up, causing the two to be swept up by a tornado, and end up inside the house with Argo. Argo complained that they weren't suppose to come up there with her, but explained her situation, and the two were pulled into a quest that she was doing. Kirito realizes that she out-ran the dog, as she was bad with dogs, but that caused the quest to become stuck. Argo realizes that the house they were in was moving, and eventually comes upon an area in the 22nd floor, that is unreachable by foot. After meeting 3 NPCs, a Tin-man, a lion, and a scarecrow, Argo and Asuna realized that this mission was based on the "Wizard of Oz."

Deciding to skip the sub-quests, Argo and Asuna decide to skip straight to the Witch's Castle, which they managed to pass through easily, due to their much higher levels. After defeating the Witch, and returning from the quest, Argo promised not to tell anyone about Kirito and Asuna's marriage, which she figured out on her own.

Trivia

 * Argo is one of the few players in SAO who have a nickname for Kirito. She likes to call him, "Kii-bou".
 * Argo was Kirito's second ever contact on his friend list (after Klein)
 * Argo seems to have a dislike towards dogs.