24화: 키리토와 유이가 아스나를 구하기 위해 오버런을 막고 세계수의 정상에서 맞선다
Arriving at the top of the World Tree, Kirito and Yui finally reunite with Asuna. However, they are suddenly hit by high gravity magic, which forces Yui to retreat, and they are confronted by Oberon. As Oberon reveals that his plans to control the human mind are almost complete, he chains Asuna and attempts to molest her in front of Kirito. Falling into despair, Kirito hears the voice of Akihiko, who encourages him to stand up and fight. Using Akihiko's administrative functions, Kirito removes Oberon's powers and challenges him to a fight with no pain absorption, showing him what true pain is, before destroying Oberon. After logging Asuna out to ensure her safety in the real world, Kirito meets with the remnant of Akihiko's memory, who gives him an item called "The Seed" before leaving. (Source: Wikipedia)