Sword Art Online: Mother's Rosary Vol. 1 (manga)

Kirito and Sinon's battle with Death Gun is over, but mere weeks later, something strange is afoot in the next-generation VRMMO ALfheim Online. A new duelist with a custom sword skill is defeating all comers--including Kirito! But when Asuna goes to face this duelist, she receives something she never expected: an invitation to an exclusive guild! But what is their aim? The Mother's Rosario arc begins!

Stage.001 - Stage.003 & Extra Episode.