Yui

About Yui

Yui began as MHCP001, an AI program built to monitor the mental health of Sword Art Online's trapped players, forbidden from helping them, she broke down watching their despair. Kirito and Asuna adopted her, and she has called them Papa and Mama ever since. Saved into Kirito's NerveGear, she now travels as a navigation pixie, fiercely protective of her family.

Appearance

Yui first appears as a small girl of about eight with long black hair and dark eyes, in a simple white dress, barefoot and lost-looking. In her saved form she travels as a navigation pixie: a tiny winged fairy a few inches tall, usually in a pink dress, riding in Kirito's breast pocket or perched on someone's shoulder or head. Her expressions are big for her size: delighted, indignant, fiercely protective by turns. She looks like a mascot; everyone who knows her treats her as what she is: Kirito and Asuna's daughter.

Personality

Yui is cheerful, curious and utterly devoted to her parents. Built to read human emotion, she understands feelings better than most humans in the story, and uses that understanding like a child would: to comfort, to scold and to keep her family together. She is brave in the specific way of someone who has already been deleted once and decided her family is worth it anyway. Her pixie form gives her a mascot's image, but in every crisis she is working: analysing, guiding and worrying, the family's youngest member and often its wisest.

Background & Story

Yui was created as MHCP001, the first Mental Health Counselling Program of Sword Art Online's Cardinal System, an AI built to monitor the trapped players' emotions and comfort them. The system forbade her from contacting the players she watched, and watching 10,000 people despair without being allowed to help drove her to breakdown; she wandered Aincrad in a child form with her memory and language collapsing. Found in a forest on the 22nd floor by Kirito and Asuna, she adopted them on the spot, and they returned the feeling, fighting to keep her when the system moved to delete her as a broken program. Saved into Kirito's NerveGear as data, she travels with her family in every world since.

Powers & Abilities

• Emotion Monitoring: As a counselling program, Yui reads players' emotional states with total accuracy. She can sense lies, fear and despair in the people around her family.
• Navigation Pixie: In ALfheim and beyond, Yui travels as a navigation pixie with system-level knowledge of maps, monsters and game data, guiding her parents through every world.

Key Relationships

• Kirito: Her Papa, the player who fought the system itself to save her data, and whose pocket is her favourite place in every world.
• Asuna Yuuki: Her Mama, Yui's first memory on waking was of Asuna's kindness, and her devotion to her mother is absolute.
• Suguha Kirigaya: Leafa, Yui's aunt in everything but paperwork, and one of her favourite people to ride with through ALfheim's skies.

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