|This article is about a/an episode in Kamen Rider Saber.|
Chapter 4: I Opened the Book, Therefore. (本を開いた、それゆえに。 Hon o Aita, Sore Yue ni.) is the fourth episode of Kamen Rider Saber. It features the debuts of Desast, Buster Genbu Jackun, the Storm Eagle and Needle Hedgehog Wonder Ride Books, Saber Dragon Hedgehog, and Saber Dragon Hedgehog Peter. Kento briefly appears as Kamen Rider Espada towards the end of the episode.
Despite defeating the Megid, the city still hasn't reverted back to normal! Touma promises a worried Ryo Ogami who is missing his son Sora, that he will get him back! Ryo's feelings manifest towards Touma by saying "Do you understand what a parent is feeling?!" Despite this, Touma still promises to keep his word. Feeling frustrated and full of intense emotions, Ryo seeks to inform the sage of what has occurred. The case of the Megid is still a mystery, and just where did these people disappear to?! Touma and Rintaro think this situation over carefully, as Mei, who feels responsibility for what happened, suddenly makes a rash decision...!
- "Bonne lecture! My name is Tassel. I'm currently excited about these two swordsmen. Ogami, who appeared before Touma, showed immense heroism and strength as the almighty King of Parenting. This guy really stands out! *coughs* The King of Parenting's child disappeared, which caused a major commotion! It seemed like Touma and the others had saved everyone, but..."
- Touma Kamiyama (神山 飛羽真 Kamiyama Tōma): Syuichiro Naito (内藤 秀一郎 Naitō Shūichirō)
- Rintaro Shindo (新堂 倫太郎 Shindō Rintarō): Takaya Yamaguchi (山口 貴也 Yamaguchi Takaya)
- Mei Sudo (須藤 芽依 Sudō Mei): Asuka Kawazu (川津 明日香 Kawazu Asuka)
- Kento Fukamiya (富加宮 賢人 Fukamiya Kento): Ryo Aoki (青木 瞭 Aoki Ryō)
- Ryo Ogami (尾上 亮 Ogami Ryō): Yuki Ikushima (生島 勇輝 Ikushima Yūki)
- Tetsuo Daishinji (大秦寺 哲雄 Daishinji Tetsuo): Hiroaki Oka (岡 宏明 Oka Hiroaki)
- Storious (ストリウス Sutoriusu): Robin Furuya (古屋 呂敏 Furuya Robin)
- Legeiel (レジエル Rejieru): Kairu Takano (高野 海琉 Takano Kairu)
- Zooous (ズオス Zuosu): Koji Saikawa (才川 コージ Saikawa Kōji)
- Kamen Rider Calibur (仮面ライダーカリバー Kamen Raidā Karibā, Voice): Hiroyuki Hirayama (平山浩行 Hirayama Hiroyuki) (Uncredited)
- Desast (デザスト Dezasuto, Voice): Kōki Uchiyama (内山 昂輝 Uchiyama Kōki)
- Tassel (タッセル Tasseru): Les Romanesques TOBI (レ・ロマネスクTOBI Re Romanesuku Tobī)
- Sophia (ソフィア Sofia): Rina Chinen (知念 里奈 Chinen Rina)
- Narrator, Seiken Swordriver, Wonder Ride Books: Akio Otsuka (大塚 明夫 Ōtsuka Akio)
- Seiken Swordriver: Eizo Sakamoto (坂本 英三 Sakamoto Eizō)
- Fighting Fairy (戦う妖精さん Tatakau Yōsei-san): Reika Saiki (才木 玲佳 Saiki Reika)
- Hanzaki Megid (ハンザキメギド Hanzaki Megido, Voice): Junji Majima (間島 淳司 Majima Junji)
- Sora Ogami (尾上 空 Ogami Sora): Tenta Banka (番家 天嵩 Banka Tenta)
- Kamen Rider Saber: Kosuke Asai (浅井 宏輔 Asai Kōsuke)
- Kamen Rider Blades: Eitoku (永徳 Eitoku)
- Kamen Rider Espada: Yuji Nakata (中田 裕士 Nakata Yūji)
- Kamen Rider Buster: Jiro Okamoto (岡元 次郎 Okamoto Jirō)
- Kamen Rider Calibur: Kenji Tominaga (富永 研司 Tominaga Kenji)
- Desast: Kazuya Okada (岡田 和也 Okada Kazuya)
- Hanzaki Megid: Danki Sakae (榮 男樹 Sakae Danki)
Forms and Collectibles Used
- Book Used:
- Brave Dragon, Needle Hedgehog, Peter Fantasista
- Lion Senki, Peter Fantasista
- Lamp Do Alangina
- Genbu Shinwa, Jackun-to-Domamenoki
- Jaaku Dragon
- Form Used:
- Dragon Hedgehog, Dragon Hedgehog Peter, Brave Dragon
- Lion Fantasista, Lion Senki
- Lamp Do Alangina
- Genbu Shinwa, Genbu Jackun
- Jaaku Dragon
- to be added
- As part of Super Hero Time, this episode aired alongside Mashin Sentai Kiramager episode 25, Episode 25: That Cute Shrine Maiden.
- Coincidentally, both episodes featured a new recurring villain.
- Closing Screen Wonder Ride Books
- Kamen Riders: Saber
- Wonder Ride Books: Needle Hedgehog
- Wonder World Text Translation Page
- Wonder Ride Books: Needle Hedgehog, Jackun-to-Domanenoki
- Count at episode end
- Wonder Ride Books in Saber's possession: Brave Dragon, Needle Hedgehog, Peter Fantasista, Diago Speedy
- Wonder Ride Books in Blades's possession: Lion Senki, Book Gate
- Wonder Ride Books in Espada's possession: Lamp do Alangina
- Wonder Ride Books in Buster's possession: Genbu Shinwa, Jackun-to-Domamenoki, Storm Eagle
- Wonder Ride Books in Calibur's possession: Jaaku Dragon
- This episode marks the first time any Rider has directly transformed from their human state using two books.
- This episode marks the first time a Rider has transformed using three books.
- This also marks the first time that Riders have dueled each other, specifically Saber, Blades, and Espada against Calibur.
- TV Asahi's official episode guide for 本を開いた、それゆえに。
- KR Official's official episode guide for 本を開いた、それゆえに。
- JAE's official episode guide for 本を開いた、それゆえに。