Asuna Yuuki

The main heroine of the work. She serves as the protagonist in the side stories. Her birthday is September 30, 2007, in the story. She lives in Setagaya, Tokyo. She is considerate of those around her, has a strong sense of self-discipline, and is a hardworking young lady who has walked the elite path. She is a beautiful girl with long chestnut hair and hazel eyes, and an outstanding figure. Although she was a novice at games, she whimsically joined SAO at the age of 15 and got caught up in the death game. The author initially wrote her to exude as much of a "good woman" vibe as possible, and she is said to have some elements of actress Chiaki Kuriyama as a model.

At the beginning of her imprisonment in SAO, she fell into a state of semi-madness but recovered with the support of her schoolmate, Mito, and acted together with her. After disbanding her party with Mito due to an unfortunate accident, she fell into depression again but was inspired to live as herself until the last moment. She met Kirito by chance while leveling up in the labyrinth area. As she teamed up with him to progress through the game, she regained her original personality, developed feelings for him, and entered into a system marriage. After the old ALO incident was resolved, she finally met Kirito in the real world and became his girlfriend, taking pride in the changes she underwent after meeting him. She continues to strive daily to be Kirito's emotional support and aims to build a family with him in the real world in the future. She generally maintains good relationships with the women who have feelings for Kirito, but she is in a cold war with Alice.

During the SAO incident, she served as the vice-commander of the Knights of the Blood Oath, showcasing her leadership talents. In the new ALO, she met Yuuki and learned the importance of facing challenges without fearing the outcome, resolving her conflicts with her mother. In UW, she spent 200 years of internal time with Kirito, ruling the world of UW as a queen, bringing peace and wisdom.

She has high virtual world adaptability, second only to Kirito, and fights using a rapier style, characterized by high-speed sword techniques. In SAO, she prioritizes clearing the game above all else, except for human life and safety, fighting on the front lines. In the new ALO, she becomes a healer but uses a hybrid build that includes close combat with a rapier.

Her avatar consistently features a rapier as a weapon, chest armor, over-the-knee socks, and a long skirt that only covers the back. In SAO, after the formation of the Knights of the Blood Oath, she wears a knight's uniform based on red and white. In the old ALO, she is dressed in a white one-piece dress that exposes her navel as the fairy queen Titania, unarmed. In the new ALO, she has light blue hair, wears a white one-piece dress, and carries a staff for magic chanting. In UW, she has an appearance similar to Titania with GM equipment and a rapier. In UR, her appearance is almost identical to ALO, but she quickly dyed her hair to a color close to reality. She equips metal armor and tames semi-aquatic monsters.