|This article is about a/an spin-off media story in Kamen Rider Ryuki.|
Advent Calendar (アドベントカレンダー Adobento Karendā) is the first Kamen Rider Ryuki Edition of S.I.C. Hero Saga, 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.
- Advent Calendar chapter titles
- Advent 4 (待降節・4 Taikōsetsu 4)
- Advent 3 (待降節・3 Taikōsetsu 3)
- Advent 2 (待降節・2 Taikōsetsu 2)
- Advent 1 (待降節・1 Taikōsetsu 1)
- Nightmare Before (ナイトメア・ビフォア Naitomea Bifoa)
With the Rider War reaching its climax, Ryuki, Knight, Ouja, Zolda and Odin are the surviving Riders left. While Ouja is fighting Knight, he crushes him under some rubble. Ryuki shows up and challenges Ouja into a fight. Using the Survive Shippu card he stole from Knight, Ouja transforms into his Survive form, with Venosnaker evolving into Venoviper.
As Yui happened to be nearby, Ouja summons Venoviper while holding Yui as its hostage. He then uses his new Unite Vent card with all the Advent cards he's gathered up until now from the Riders he defeated, with the Darkwing card also stolen from Knight. All of his monsters, as well as Dragreder, who just happened to be nearby, combine to form Genosurviver. However, since Dragreder still belongs to Ryuki, its head starts snapping at Venoviper's head. When Genosurviver starts to run out of control, it tries to attack and destroy Mirror World.
Kitaoka shows up saying that he knew "something weird" was going on in Mirror World, since he was in his car when its windscreen just cracked. He transforms into Zolda, summons Magnugiga and performs the End of World, killing Ouja, Genosurviver and himself.
Ryuki sees the rubble with Knight under it. At that moment, he is possessed by the spirit of his deceased older brother, Shinichi Kido. Looking at the dead bodies of Ouja and Zolda, Yui says he did it, and while it happened, he and Dragreder had turned black.
Ren shows up intact, revealing that the Knight that Ouja defeated was a Trick Vent copy. Now that Shinji, still possessed by Shinichi, and Ren are the last remaining Riders, they fight with Shinji as the victor. Odin (who merely serves to grant the winner of the Rider War's wish) appears, granting Shinji's wish: to revive all of the victims of the Rider War.
|Kamen Rider Ryuki||Shinji Kido|
|Kamen Rider Ryuga||Shinji Kido (possessed by Shinichi Kido)|
|Kamen Rider Knight||Ren Akiyama|
|Kamen Rider Ouja||Takeshi Asakura|
|Kamen Rider Zolda||Shouichi Kitaoka|
|Kamen Rider Odin||Kamen Rider Odin|