|This article is about a/an episode in Kamen Rider Den-O.|
Reliving a Blank Day (甦る空白の一日 Yomigaeru Kūhaku no Ichinichi) is the forty-fifth episode of Kamen Rider Den-O.
Ryotaro tries to find a way to travel back to the day his sister lost her memory, in hopes that it would reveal the full truth regarding what happened to her and to her fiance Sakurai.
While getting the Milk Dipper ready for Christmas, Ryotaro receives a package holding a pocket watch, identical to the one Sakurai gave to Airi. Learning that the watch was sent to him by himself, with no recollection of the act, Ryotaro heads to the clock shop he and Airi went to last year for Sakurai's watch to get to the bottom of it. Learning that last year he ordered the watch for August, Ryotaro is even more confused and remembers Owner's words about his memory before going to find Yuto to take him to the day Airi lost her memory. But as Yuto refuses to help Ryotaro, hiding something from him, the clock shop owner inadvertently opens a contract with the Snowman Imagin. Once learning of the Snowman Imagin, Den-O Sword Form intercepts the Imagin and is unable to keep it from going back in time as he attempted not to destroy the Santa balloon in the vicinity. But in spite of Yuto's pleas not to, Ryotaro goes back in time to January 10, 2007, the day Sakurai disappeared and Airi lost her memory, to learn what truly happened. Once assuming Liner Form, Den-O destroys the Snowman Imagin and then Ryotaro heads to the lake where Sakurai disappeared. When he arrives, he sees Sakurai, as Zeronos Altair Form, fighting off a trio of Leo Soldiers before Kai opens a time pulse with the ZeroLiner covering Ryotaro and Yuto. In the midst of the explosion, Ryotaro sees Airi before she and Sakurai fade out of existence with the rest of the area. Only Ryotaro and Yuto remain, watching a jubilant Kai celebrating his victory on the desert wasteland.
- Den-O: Sword Form, Plat Form, Liner Form
- Zeronos (Past): Altair Form
- Ryotaro Nogami (野上 良太郎 Nogami Ryōtarō): Takeru Satoh (佐藤 健 Satō Takeru)
- Kohana (コハナ Kohana): Tamaki Matsumoto (松元 環季 Matsumoto Tamaki)
- Yuto Sakurai (桜井 侑斗 Sakurai Yūto): Yuichi Nakamura (中村 優一 Nakamura Yūichi)
- Naomi (ナオミ Naomi): Rina Akiyama (秋山 莉奈 Akiyama Rina)
- Airi Nogami (野上 愛理 Nogami Airi): Wakana Matsumoto (松本 若菜 Matsumoto Wakana)
- Kai (カイ Kai): Hideo Ishiguro (石黒 英雄 Ishiguro Hideo)
- Momotaros (モモタロス Momotarosu, Voice): Toshihiko Seki (関 俊彦 Seki Toshihiko)
- Urataros (ウラタロス Uratarosu, Voice): Kōji Yusa (遊佐 浩二 Yusa Kōji)
- Kintaros (キンタロス Kintarosu, Voice): Masaki Terasoma (てらそま まさき Terasoma Masaki)
- Ryutaros (リュウタロス Ryūtarosu, Voice): Kenichi Suzumura (鈴村 健一 Suzumura Ken'ichi)
- Deneb (デネブ Denebu, Voice): Hōchū Ōtsuka (大塚 芳忠 Ōtsuka Hōchū)
- Opening Narration (オープニングナレーション Ōpuningu Narēshon): Kenjirō Ishimaru (石丸 謙二郎 Ishimaru Kenjirō)
- Clock Shopkeeper: Ryo Ono (小野 了 Ono Ryō)
- Man: Ryutaro Kikuchi (菊地 隆太郎 Kikuchi Ryutarō)
- Victim: Yusei Maruyama (丸山 裕征 Maruyama Yūsei)
- Snowman Imagin (スノーマンイマジン Sunōman Imajin, Voice): Tōru Ōkawa (大川 透 Ōkawa Tōru)
- Albinoleo Imagin (アルビノレオイマジン Arubinoreo Imajin): Takaya Kuroda (黒田 崇矢 Kuroda Takaya)
- Kamen Rider Den-O/Momotaros: Seiji Takaiwa (高岩 成二 Takaiwa Seiji)
- Urataros: Eitoku (永徳 Eitoku)
- Kintaros: Jirō Okamoto (岡元 次郎 Okamoto Jirō)
- Ryutaros: Toshihiro Ogura (おぐら としひろ Ogura Toshihiro)
- Kamen Rider Zeronos: Makoto Ito (伊藤 慎 Itō Makoto)
- Deneb: Yoshifumi Oshikawa (押川 善文 Oshikawa Yoshifumi)
- Snowman Imagin, Albinoleo Imagin: Norihito Itō (伊藤 教人 Itō Norihito)
- As part of Super Hero Time, this episode aired alongside Juken Sentai Gekiranger episode 42, Lesson 42: Wasshi-Wasshi Moving On!.
- Viewership: 6.2%
Blu-ray Box 3 comes with 13 episodes.