Ep. 12: Kirito and Asuna rescue Thinker while Yui sacrifices her existence as an AI.

While resting at the church with Sasha, Kirito and Asuna are visited by Yulier, the Army's second-in-command. She explains that leader Thinker was trapped in a first-floor dungeon by Kibaou following the Gleam Eyes incident, prompting a request for their assistance. Upon reaching Thinker, the pair faces the Fatal Scythe boss. Yui intervenes to protect Kirito, proving herself an Immortal Object immune to damage that would lower her health to the yellow zone. This event triggers her memory recovery, revealing her true nature as an artificial intelligence. Although Kirito and Asuna accept her as their daughter, Yui prepares for deletion due to her interference. Kirito refuses to let her disappear, using a Gamemaster console to transfer her data into a game item named "Yui's Heart."

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