|This article is about a/an episode in Kamen Rider Gaim.|
|WARNING: This episode contains scenes of blood, graphic violence, character death, and alcohol drinking. Viewer discretion is advised!|
Baron's Ultimate Transformation (バロン 究極の変身 Baron Kyukyoku no Henshin) is the forty-third episode of Kamen Rider Gaim. This episode marks Kaito's transformation into an Inves, Lord Baron. Mai's relationship with the Woman of the Beginning is also revealed. It also features the final appearance of Kamen Rider Ryugen Yomi and Ryoma Sengoku.
As Gaim and Ryugen Yomi continue their battle, Kaito realizes that there is only one way for him to surpass Kouta now that he possesses the powers of the Over Lord King.
Continued from the previous episode, Ryugen Yomi still tried to fight Gaim while having his life slowly consumed by the Yomotsuheguri Lockseed despite Gaim's warning not to do it. Mai dreamed of herself in Team Gaim's garage and visited by DJ Sagara whom told her that she is in possession of the Forbidden Fruit and that she can use it to do anything on her ideals. While Professor Ryoma begins operating on Mai, both Ryugen Yomi and Gaim initiates their finishers but as they are about to attack each other, Gaim throws his Musou Saber and reaches the Yomotsuheguri Lockseed to remove it from Ryugen Yomi at the cost of his own life. Surprised by his former friend's action, Mitsuzane asked why as Kouta told him that he had already forgiven his actions and advised the latter to forgive himself before he seemingly died. Mitsuzane realized he still had more time left and went back to Mai. Chucky and Peko arrived at the Team Gaim garage, spreading the bad news to Kaito and Yoko about Mai. Entering the hospital where Mai's operation took place, Ryoma reported that the operation was a success and delighted to hear of Mitsuzane's progress. As he went to Mai, he realized that she had died in the operation as Ryoma never intended to save her but only to take the fruit away since it had completely fused with her heart. Angered that all of his efforts were in vain, Mitsuzane attempts to transform into Zangetsu Shin but Ryoma quickly disables the Genesis Driver by activating a kill switch he'd installed, knowing that he would someday duel with another user of his creation. Ryoma then starts to give Mitsuzane a beating while comparing his foolishness to his brother, before attempting to strangle him. The Forbidden Fruit prevents this when it erupts and transforms into a spectral Mai where she forgives Mitsuzane for his past actions and disappears before Mitsuzane can reach her. Mai travels back in time while Sagara calling her actions as crazy though it said it wasn't impossible. Mai arrives in the time where Gaim's debut as Kachidoki Arms battled against Kurokage Troopers on the Yggdrasill Tower and met the past DJ Sagara, asking why he encouraged Kouta. Sagara replied that this was all a plan to see whose worth in obtaining the Forbidden Fruit. As Kaito and Yoko arrived late, they discover a crying Mitsuzane beside Mai's corpse and a crazed Ryoma Sengoku trying to calculate the current location of the Forbidden Fruit. Disgusted over the professor's actions, they tried to transform but Ryoma quickly disables their Genesis Drivers. However Kaito still has his Sengoku Driver and transforms into Banana Arms to fight Ryoma, who transforms into Duke. only to find himself struggling with the Helheim infection. Despite his best attempts, the Sengoku Driver simply does not have enough power to keep up with Duke and Kaito is defeated. As Ryoma mocked him for the infection, Kaito remembers the pains he went through all along in his life and decides to eat the Helheim Fruit (while bringing up Hase's incident), transforming himself into an Over Lord Inves called Lord Baron. Surprised by Lord Baron's ability to retain his mind, Ryoma quickly transforms and fights but is quickly overpowered by the Over Lord's immense power. Ryoma warns Kaito of the danger for abandoning his humanity before falling to his death. Still, Kaito refuses to surrender and decides to meet his fate head-on, while a still loyal Yoko picks up Ryoma's Genesis Driver to replace her own.
- Kouta Kazuraba (葛葉 紘汰 Kazuraba Kōta): Gaku Sano (佐野 岳 Sano Gaku)
- Kaito Kumon (駆紋 戒斗 Kumon Kaito): Yutaka Kobayashi (小林 豊 Kobayashi Yutaka)
- Mitsuzane Kureshima (呉島 光実 Kureshima Mitsuzane): Mahiro Takasugi (高杉 真宙 Takasugi Mahiro)
- Mai Takatsukasa/Woman of the Beginning (高司 舞/始まりの女 Takatsukasa Mai/Hajimari no Onna): Yuumi Shida (志田 友美 Shida Yuumi)
- Chucky (チャッキー Chakkī): KANON
- Peko (ペコ Peko): Saku Momose (百瀬 朔 Momose Saku)
- Ryoma Sengoku (戦極 凌馬 Sengoku Ryōma): Tsunenori Aoki (青木 玄徳 Aoki Tsunenori)
- DJ Sagara (DJサガラ Dī Jei Sagara): Tomomitsu Yamaguchi (山口 智充 Yamaguchi Tomomitsu)
- Yoko Minato (湊 耀子 Minato Yōko): Minami Tsukui (佃井 皆美 Tsukui Minami)
- Sengoku Driver Equipment Voice (戦極ドライバー各種アイテム音声 Sengoku Doraibā Kanren Aitemu Onsei): Seiji Hiratoko (平床 政治 Hiratoko Seiji)
- Genesis Driver Equipment Voice (ゲネシスドライバー各種アイテム音声 Geneshisu Doraibā Kanren Aitemu Onsei): Shin-ichiro Miki (三木 眞一郎 Miki Shinichirō)
- Narration (ナレーション Narēshon): Hōchū Ōtsuka (大塚 芳忠 Ōtsuka Hōchū)
- Lock used:
- Kachidoki, Kiwami, Orange (in Musou Saber)
- Lemon Energy (destroyed), Banana
- Ryugen Yomi:
- Yomotsuheguri (destroyed)
- Lemon Energy
- Arms Change:
- Weapons summoned in Kiwami Arms:
- Weapons summoned in Yomotsuheguri Arms:
- While in the episode's promo, Mai is seen floating in the air in person, the episode proper shows her meeting them in a spirit-like form.
- This is similar to Sagara meeting the Over Lords in person in the promo of the beginning of the Over Lord saga.
- As part of Super Hero Time, this episode aired alongside Ressha Sentai ToQger episode 26, Station 26: The Fight that Started in a Bathhouse.
- Viewership: 3.7%
- Closing Screen Lockseed Collection:
- Clips from the Woman at the Beginning's appearances in episodes 1, 3, and 5 are used in this episode.
- Ryoji Hase is brought up by Kaito before he eats one of Helheim's Fruits.
- This episode's title is the fourth with "Baron" as the first word.