Sword Art Online

At the daycare center inside a church, Kirito, Asuna, Yui and Sasha are visited by Yulier, second-in-command of the Aincrad Liberation Force. Yulier explains that Thinker, leader of the Aincrad Liberation Force, was overthrown by Kibaou, who trapped Thinker in a dungeon on the 1st Floor three days ago. Kirito, Asuna and Yui agree to help Yulier rescue Thinker. As they clear the dungeon and find Thinker, they are ambushed by a boss named the Fatal Scythe. Kirito and Asuna attempt to fight the Fatal Scythe, but are completely outmatched and overwhelmed. Yui steps in and destroys the Fatal Scythe in a ball of fire, revealing that she is an indestructible in-game object. Kirito and Asuna discover that Yui is an artificial intelligence character designed to aid the players, but was forced to monitor them instead. Yui admits that she felt like a daughter to Kirito and Asuna when she interacted with them. Yui is then sentenced to deletion due to her interference with the game, but Kirito manages to use the gamemaster console to save Yui from complete deletion by transforming her data into an in-game item, a crystal drop that he gives to Asuna.