In Zawame City (沢芽市, Zawame-shi), a large company known as the Yggdrasill Corporation transformed the once bustling suburban city into a 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 the meantime, 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.