Kamen Rider Bujin Gaim is one of the fifteen Bujin Riders who domain over the World of the Sengoku Period and the main antagonist of Kamen Rider × Kamen Rider Gaim & Wizard: The Fateful Sengoku Movie Battle. He seeks to kill the other fourteen Bujin Riders to claim "Heaven's Power" and rule over the Sengoku World alone.
Commanding an army of monsters, Kamen Rider Bujin Gaim suddenly appeared in the World of the Sengoku Period one day and began targeting the other Bujin Riders to claim their powers.
After defeating Bujin OOO and having him eaten by the Pitcher Plant Monster, Bujin Gaim encounters Gaim and Ryugen, who entered the World of the Sengoku to save Mai. The two Armored Riders beat back his armies and force him to retreat.
The next day, Bujin Gaim goes after Bujin Double and wins his fight with him after Armored Rider Zangetsu mistakes Bujin Gaim as the regular Gaim and intervenes. Zangetsu soon realizes that Bujin Gaim is not his Gaim after seeing that Bujin Gaim is allied with the Pitcher Plant Monster. The two attempt to capture Zangetsu but the Armored Rider manages to slip away.
Bujin Gaim's next move is to open a crack to Wizard's world and have the Pitcher Plant Monster eat Kousuke, causing Haruto to go after him as well. Bujin Gaim later attacks and defeats Bujin Fourze but is soon confronted by Kamen Rider Gaim again. Kouta is then forced to escape using the Suika Lockseed (from Ryugen before being absorbed) and takes Ieyasu to safety.
After sacrificing every Bujin Rider to the God Tree to gain control of it, Bujin Gaim attempts to capture Mai, believing her to be the "Priestess of Fate", but is confronted by Gaim, Baron and Wizard. After defeating the Pitcher Plant Monster to rescue its captives, the six Kamen Riders go to confront Bujin Gaim. However, Bujin Gaim still proves too powerful for them and overwhelms before going to capture Mai again. He later merges with the God Tree to claim more power and with it easily defeats Kamen Riders Gaim and Wizard.
Bujin Gaim then attempts to finish off the two Riders by having the God Tree consume them, but the two break free with the power of the other Bujin Riders, resulting in Bujin Gaim being weakened. After being beaten down by the two Kamen Riders, Bujin Gaim is finished off by Wizard's Strike Wizard and Gaim's Burai Kick.