|This article is about a/an episode in Kamen Rider Fourze.|
Youthful Transformation (青・春・変・身 Sei・Shun・Hen・Shin) is the first episode of Kamen Rider Fourze, introducing the series' setting and the initial main cast following the appearances of Gentaro Kisaragi and Yuki Jojima in Kamen Rider OOO Wonderful: The Shogun and the 21 Core Medals and Yuki and Kengo Utahoshi in the finale of OOO. It is the first part of the initial Orion arc.
The new school year begins at Amanogawa High School, and Kengo Utahoshi is detecting strange energies around the school. And things get stranger when yankee-looking Gentaro Kisaragi transfers into the school and decides that he wants to be Kengo's friend.
The new school year begins at Amanogawa High School, as Kengo Utahoshi encounters a strange delinquent who chides him for throwing a girl's love letter into the river. Later, at Ms. Sarina Sonoda's homeroom class while he using a Burgermeal Foodroid to analyze strange energy readings, Kengo encounters the delinquent as he introduces himself to the class as the new transfer student Gentaro Kisaragi. Despite his scary appearance, Gentaro is a nice guy as he recognizes his childhood friend Yuki Jojima, greeting each other with a special handshake, before giving the soaked letter to Kengo with intentions of being Kengo's friend. Refusing to accept Gentaro's offers of friendship, Kengo walks out of class, much to Ms. Sonoda's dismay. Tracking down Kengo, Gentaro arrives at the cafeteria where he meets JK, while making enemies out of the head cheerleader Miu Kazashiro and her boyfriend Shun Daimonji, the captain of the American football team. Gentaro proceeds to defend himself from the football team before he is forced to let himself be Shun's tackle dummy when Yuki is captured. However, a monster appears from out of nowhere and attacks the group.
The football team runs for it as Gentaro fights the monster, but he is seemingly knocked out. Kengo arrives to even the odds in the Powerdizer exo-suit, and Yuki identifies the monster as the Orion Zodiarts. Physically strained from using the suit, Kengo is unable to pursue the escaping monster. After putting the Powerdizer away, Kengo and Yuki enter a concealed locker that transports them to the Rabbit Hatch lunar base, with Kengo intending to use the Fourze Driver. However, the two discover that they were followed by Gentaro who takes the Fourze Driver instead, while elsewhere the Orion Zodiarts resumes his attack on the school.
With Kengo unable to chase him due to his health, Yuki finds the clueless Gentaro as he faces the Orion Zodiarts and directs him to transform into Fourze. Fourze and the Zodiarts begin fighting in the mens' locker room before Fourze uses the Rocket Module to force the Orion Zodiarts off campus. Gentaro begins to get used to the abilities of Fourze, with Kengo's directions in using the different Astroswitches, before he uses a combination of the Rocket and Drill Switches to initiate the Rocket Drill Kick Limit Break, defeating the Orion Zodiarts. However, the victory falls short when Kengo arrives in the Powerdizer once more with the intent to take the Fourze Driver back from Gentaro by force.
- Gentaro Kisaragi (如月 弦太朗 Kisaragi Gentarō): Sota Fukushi (福士 蒼汰 Fukushi Sōta)
- Kengo Utahoshi (歌星 賢吾 Utahoshi Kengo): Ryuki Takahashi (高橋 龍輝 Takahashi Ryūki)
- Yuki Jojima (城島 ユウキ Jōjima Yūki): Fumika Shimizu (清水 富美加 Shimizu Fumika)
- Miu Kazashiro (風城 美羽 Kazashiro Miu): Rikako Sakata (坂田 梨香子 Sakata Rikako)
- Shun Daimonji (大文字 隼 Daimonji Shun): Justin Tomimori (冨森 ジャスティン Tomimori Jasutin)
- Tomoko Nozama (野座間 友子 Nozama Tomoko): Shiho (志保)
- JK (ＪＫ（ジェイク） Jeiku): Shion Tsuchiya (土屋 シオン Tsuchiya Shion)
- Sarina Sonoda (園田 紗里奈 Sonoda Sarina): Yuka Konan (虎南 有香 Konan Yuka)
- Chuta Ohsugi (大杉 忠太 Ōsugi Chūta): Takushi Tanaka (田中 卓志 Tanaka Takushi)
- The Red-Eyed Man (赤い目の男 Akai Me no Otoko): Shingo Tsurumi (鶴見 辰吾 Tsurumi Shingo)
- Narration (ナレーション Narēshon): Nobuyuki Hiyama (檜山 修之 Hiyama Nobuyuki)
- Toshiya Miura (三浦 俊也 Miura Toshiya): Masanori Mizuno (水野 真典 Mizuno Masanori)
- Tamae Sakuma (佐久間 珠恵 Sakuma Tamae): Maria Yoshikawa (吉川 まりあ Yoshikawa Maria)
- Jun Shigeno (繁野 ジュン Shigeno Jun): Arisa Fujisaki (藤嵜 亜莉沙 Fujisaki Arisa)
- Girl with Love Letter: Mayu Tomita (冨田 真由 Mayu Tomita)
- Yuki Jojima (Child): Kanon Kasuga (春日 香音 Kasuga Kanon)
- 2B Members: Iijima Ramu (飯嶋 羅夢 Iijima Ramu), Seiya Iwaoka (岩岡 誠也 Iwaoka Seiya), Manami Iwashita (岩下 愛実 Iwashita Manami), Nanako Ohto (大戸 菜々子 Ōto Nanako), Masafumi Ohyama (大山 聖文 Ōyama Masafumi), Hina Kaneko (金子 妃菜 Kaneko Hina), Sanae Kaneno (金野 沙奈江 Kaneno Sanae), Satoshi Kikuchi (菊地 悟司 Kikuchi Satoshi), Akiko Koga (古賀 安貴子 Koga Akiko), Mizuki Kobayashi (小林 瑞紀 Kobayashi Mizuki), Masahiro Saita (斉田 雅宏 Saita Masahiro), Masaki Shiiba (椎葉 昌紀 Shiiba Masaki), Konomi Suzuki (鈴木 このみ Suzuki Konomi), Tetsutaro Suzuki (鈴木 鐵大郎 Suzuki Tetsutarō), Kenta Takahashi (高橋 健太 Takahashi Kenta), Saki Tanaka (田中 沙季 Tanaka Saki), Nemu Nakagawa (仲川 子夢 Nakagawa Nemu), Hasegawa Ami (長谷川 亜美 Hasegawa Ami), Ryo Hatakeyama (畠山 遼 Hatakeyama Ryō), Mebae Hoshino (星野 芽生 Hoshino Mebae), Hayato Yamada (山田 隼 Yamada Hayato), Ibuki Yoshida (吉田 伊吹 Yoshida Ibuki)
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- As part of Super Hero Time, this episode aired alongside Kaizoku Sentai Gokaiger episode 28, Ep. 28: Wings are Eternal.
- Viewership: 6.3%
- On the blackboard, the date is written as September 2nd, two days before the series premiere.
- The episode starts with an eyecatch of Kamen Rider 1 doing his signature pose with his logo in the background and music from the original show. This was to commemorate the franchise's 40th anniversary.