Sword Art Online Progressive Canon of the Golden Rule, Vol. 2 (manga) — Reki Kawahara

Asuna and Kirito narrowly thwarted Morte and his PK gang's assassination attempt! To solve the mystery of the dangerous poison pick he used in the attack, they head for the dark elf stronghold standing tall amidst the wasteland, Castle Galey. And after reuniting with their comrade Kizmel, she tells them all about Elven folklore -- revealing an unexpected connection between the PK gang and the Fallen Elves...