Sword Art Online Novel Volume 27 is written by Reki Kawahara.

After two hundred years, Kirito is finally reunited with Selka, Ronie and Tiese, but the girls are shocked to see Eolyne, who bears a striking resemblance to their fallen comrade. Then, with no time to process their feelings, the three Integrity Knights are thrown into battle alongside Eolyne and the Integrity Pilots. The old defenders of the Underworld join the new as the next chapter of the Unital Ring arc commences!