Kamen Rider Ryuki: Advent Calendar (仮面ライダー龍騎 -アドベントカレンダー- Kamen Raidā Ryūki: Adobento Karendā) was the first of two separate S.I.C. Hero Saga side stories published in Monthly Hobby Japan magazine. It featured original characters Kamen Rider Ouja Survive (仮面ライダー王蛇サバイブ Kamen Raidā Ōja Sabaibu) and his Mirror Monster Genosurviver (ジェノサバイバー Jenosabaibā). Advent Calendar ran from August to December 2004.