Trademarks on Kamen Rider Gaim were requested in May 2013, and the show was officially announced on July 25, 2013. The series producer, Naomi Takebe, wanted Gaim to return to the style of early Heisei era series, in which multiple Riders are featured. Drawing inspiration from the Sengoku period, Bandai presented the idea of using fruits as a core theme to Takebe, which led to the creation of the Arms Change.
Takebe approached Gen Urobuchi, known for Puella Magi Madoka Magica and Fate/Zero, to serve as the series main writer, and Ryuta Tasaki, who had previously worked on Kamen Rider Agito and Kamen Rider Ryuki, to direct. In an interview, Urobuchi states that Takebe requested that the series not follow the two-episode structure of recent series, as well as saying that he hopes to create the same kind of excitement he felt from Kamen Rider Black to a new generation. Urobuchi's company Nitroplus also assisted with designs.
The show's lead role went to 2011 Junon Super Boy Contest Grand Prix winner Gaku Sano, portraying Kouta Kazuraba. Sano said that he grew up wishing he could be the character from Kamen Rider Kuuga, and now that he will portray Kamen Rider Gaim he hopes that he will inspire a new generation of boys. Rounding out the main cast are Yutaka Kobayashi as Kaito Kumon/Kamen Rider Baron, Mahiro Takasugi as Mitsuzane Kureshima/Kamen Rider Ryugen, Yuumi Shida from idol group Yumemiru Adolescence as the heroine Mai Takatsukasa, and Yuki Kubota as Takatora Kureshima/Kamen Rider Zangetsu.
In Zawame City (沢芽市,Zawame-shi?), a large company known as the Yggdrasill Corporation transformed the once bustling suburban city into a castle town (城下町,城下町?, jōkamachi). To escape the resulting feeling of oppression, many of the youth in Zawame formed dance crews called Beat Riders to bring joy back into peoples' lives. Also rising in popularity is the Inves Game, a simulator that uses strange devices known as Lockseeds to summon monsters known as Inves.
Kouta Kazuraba, a member of the dance group Team Gaim, tries to find his place in the world while torn between his loyalty to his teammates and his sister Akira's insistence that he starts acting like an adult and find a proper job. When Team Gaim's captain disappears after informing Kouta of a strange belt he found, Kouta discovers that the Lockseeds and Inves are from an alternate dimension known as Helheim Forest. Encountering a mysterious girl resembling his Team Gaim teammate and close friend Mai Takatsukasa, Kouta uses a Sengoku Driver belt and the Orange Lockseed to become a samurai-armored warrior that is later named Armored Rider Gaim.
In time, including Team Baron's leader Kaito Kumon as Armored Rider Baron and Kouta's Team Gaim teammate Mitsuzane Kureshima as Ryugen, other Armored Riders appear to amass social power throughout Zawame: Team Raid Wild's Ryoji Hase as Kurokage, Team Invitto's Hideyasu Jonouchi as Gridon, and the perfectionist ex-soldier Oren Pierre Alfonzo as Bravo. Unbeknownst to the Armored Riders, the Yggdrasill Corporation monitors them and the Inves Games while the head of its R&D division, Mitsuzane's older brother Takatora, is the enigmatic white Armored Rider Zangetsu who is protecting a dark secret hidden within Helheim Forest.
Eventually, when Kouta confronts Takatora as he becomes a New Generation Armored Rider alongside the Armored Rider development scientist Ryoma Sengoku as Duke, his aide Yoko Minato as Marika, and the Lockseed Dealer Sid as Sigurd, he learns the horrible truth of Helheim Forest: that it was home to a once prosperous civilization that was eradicated by the strange plants growing throughout it, as anyone who consumed the fruit of these plants is turned into an Inves.
Finding an ally in DJ Sagara, a pirate radio DJ who knows more than he is letting on such as the intelligent Over Lord Inves, Kouta finds himself in the middle of a Sengoku period-like brawl among various factions for the right to possess the power of Helheim Forest–the proverbial forbidden fruit itself–and the fate of life on Earth as he knows it. But while adamant to obtain the Golden Fruit to save the world, Kouta's goal involves him having a predestined confrontation with Kaito who desires the fruit's power to shatter the status quo of the world.
The episodes in this Kamen Rider Series installments incorporate the name of a fruit somewhere early on in the series, as well as 2 exclamation points in the title also early on, one for the exclamation, and the other for the other half of the episode title. episode 30 takes place between episode 28 and episode 29, serving as a promotional episode.
The series is divided into five story arcs titled Sagas (編,Hen?), much like a manga/anime series.
This is the first Kamen Rider series to fully utilize the "A Rider can use other Riders' powers" more freely than Kamen Rider Decade. While Decade has to be acknowledged by the Riders themselves to use their powers, Gaim Riders need the lockseed and appropriate driver, if not already in their possession.
This is the first Kamen Rider series since Kamen Rider Kiva whose title is not an English word nor based on an English word.
While the Gaim Riders' motif is fruit, it is not the first series to have a Rider with a fruit motif. The first one is Kamen Rider Den-O, with the peach-themed Sword Form.
This Kamen Rider series does not intend to strictly follow the two-episode story arc structure that has been part of the Kamen Rider franchise since Den-O.
Most of the Riders' Transformation segments are similar to the Riders from Den-O.
Coincidentally, the voice for one of the Drivers and the Narrator are former Imagin voice actors from Den-O.
With a total of 20 Riders plus the Kurokage Troopers, Gaim not only has more Riders than any Neo-Heisei series, but has beat Ryuki (which had a total of 13 Riders, along with the 2 Alternatives), Kabuto(which had 11 Riders, not counting ZECTroopers), and Hibiki (which had 19 Riders, however it had more if you count the novel and S.I.C. saga) which makes Gaim the series with the most Riders seen on screen with 21 Riders.
Interestingly before episode 32, this series is more focused on Kamen Riders battling each other than Kamen Rider Ryuki.
Later since episode 32, the series' story becomes something similar to Kamen Rider Hibiki, and Ryuki's USA adaption Kamen Rider Dragon Knight, where most of All Riders are gathered in form of an alliance, with one/another Rider(s) on a villain sides.