During a battle in Ordinal Scale (OS), something happens to Asuna and she loses her memories of SAO. Even worse, similar symptoms begin to show up in other SAO returnees as well!? Meanwhile, Kirito is going to more OS battles to find the elusive Eiji, a young man who seems to hold the key to restoring Asuna's memories. There, he meets the mysterious girl he encountered in Yoyogi Park, who leads him to a certain place...