Yuuki Asuna

Yuuki Asuna (結城明日奈) is the main heroine and the partner of Kirito in the Sword Art Online series. She is known as Asuna (アスナ), the sub-leader of the Knights of Blood guild in «Sword Art Online». She is the daughter of the CEO of RECTO Progress Inc. She's the wife of Kirito in-game and Kirito is her boyfriend in the real world.

Background
She logged in SAO after she borrowed her brother's Nerve Gear when he had a sudden business trip and could not play on the opening day. When she discovered all the players were trapped in SAO she held herself up inside her room in «Starting City» for a week, before resolving to take fate into her own hands. This led her to kill monsters at an incredible rate and level up in a quick fashion. It also earned her the title as «Flash» (閃光).

She used to be engaged to Sugou Nobuyuki.

Reality and SAO
She has long brown hair and hazel eyes, in SAO she wears the red and white uniform of all Knight of Blood, and wields a white blade called «Lament Light».

ALfheim Online
She is an undine with a blue hair and appearance like the one in SAO.

Aincrad Arc
In SAO she is the subleader of the Knights of Blood, and makes her first appearance offering to cook Kirito's Ragout Rabbit.