is a Japanese tokusatsu series that serves as the 27th installment in the Kamen Rider franchise and the 18th entry in the Heisei era, also commemorating the 45th anniversary of the franchise. The series centers on a conflict between humans and Bugsters, a form of computer virus that infects humans playing Genm Corporation (Genm Corp.) video games. Genm Corp. and the Ministry of Health counter the threat by developing Gamer Drivers and Rider Gashats for doctors to save their patients from the Bugster Viruses.
Main characters Emu Hojo , also known by his gaming tag of , is a master gamer and pediatrics intern, later surgical intern, who had been inspired to become both after receiving a life-saving surgery and a WonderSwan handheld console from Kyotaro Hinata. Emu is well-meaning and friendly, but also clumsy and absent-minded, which often gets him into trouble with nurses. As the series progresses, however, he matures and becomes less naive, picks up Kiriya Kujo's lying habit, and becomes a master manipulator comparable to Kuroto and Masamune Dan.
16 years prior to the series, the antisocial Emu had found solace in designing video game characters. After sending his concepts to Genm Corp. game designer, Kuroto, Emu received a prototype game that infected him with and turned him into patient zero for the Bugster Virus. As a result, an alternate persona called Parado manifested from Emu's desire for a playmate and assumed control, leading to the latter becoming "M" and being kidnapped by Next Genome scientists who had sought to extract the Bugster Virus for Kuroto. However, Parado had turned into a Bugster and separated himself from Emu, allowing the latter to pursue his desire to become a doctor and earn an internship at Seito University Hospital. Despite being separated from Parado, trace amounts of the Bugster's data causes Emu to maintain his gamer persona, become a Kamen Rider, and later grant him the ability to create Gashats from his imagination. After being recruited by CR, Emu has several encounters with Parado, discovers what had happened to him, and joins forces with Parado and other Gamer Riders to defeat the Bugsters and Masamune.
Utilizing the Gashat in conjunction with the Gamer Driver, Emu can transform into Kamen Rider Ex-Aid Level 1. In this form, he gains superhuman jumping and can transform further into Action Gamer Level 2. In both forms, he wields the , which can switch between and . Moreover, activating Mighty Action X generates a Game Area with several Energy Items randomly hidden inside chocolate block-like containers. He can also combine Mighty Action X with additional Gashats to achieve stronger forms, which are as follows: : An auxiliary form accessed from the Mighty Action X and Gashats that equips Emu with the self-propelling gauntlet. : An auxiliary form accessed from the Mighty Action X and Gashats along with up to three other Gamer Riders that equips Emu with the pyrokinetic helmet. : An enhanced version of Hunter Action Gamer Level 5 (Dragon Fang) that equips Emu with the Drago Knight Blade and Gun. Sports Action Gamer Level 3: An auxiliary form accessed from the Mighty Action X and Shakariki Sports Gashats that grants similar capabilities as Kuroto's version. : An auxiliary form accessed from the Mighty Action X and Gashats that equips Emu with a pair of roller skate-like sabatons and the forearm-mounted and condiment bottles. : A special form accessed from the Mighty Action X and Gashats that equips Emu with a pair of gauntlets. This form appears exclusively in the web-exclusive special Kamen Rider Genm: Legend Gamer Stage. : A special form accessed from the Mighty Action X and Gashats that grants superhuman speed. In this form, Emu wields the Front and Rear Armed Units. This form appears exclusively in the Kamen Rider Lazer Hyper Battle DVD special.
Additionally, Emu can assume the following forms by using unique Gashats in place of Mighty Action X: and : A chibi-like evolution of the Action Gamer forms and its subsequent sleeker upgrade, both of which are accessed from the double-sized Gashat. The latter form splits Emu into the azure-colored Double Action Gamer Level XX L, which represents his level-headed doctor personality who prioritizes his patient's safety, and the orange-colored Double Action Gamer Level XX R, which represents his and/or Parado's hot-blooded gamer personality who prioritizes defeating their opponent to ensure victory. In this and all subsequent forms, he wields the , which can switch between Blade Mode, , and . Double Action Gamer Level XX first appears in the crossover film Kamen Rider Heisei Generations: Dr. Pac-Man vs. Ex-Aid & Ghost with Legend Rider. : Emu's super form accessed from the double-sized Gashat that transforms him into his Action Gamer Level 2 form clad in the exosuit, which is capable of flying, extending its limbs, and grants the ability to rewrite a Bugster's coding, depower most other Gamer Riders, and heal any Game Disease victims. He can also separate from and put the Maximum Gama on autopilot while maintaining his Level 99 power. His finisher in this form is the . : An evolution of Maximum Gamer Level 99 and Emu's final form accessed from the Maximum Mighty X Gashat combined with the adapter-like Gashat that grants warp speed capabilities and immunity to negative status effects and/or abilities, such as Kamen Rider Cronus' chronokinesis. His finisher in this form is the . Alternatively, any one of the Gamer Riders can combine Hyper Muteki with their personal Gashats to gain invincibility via the former's , which has a 10 second time limit. Levels 1 and 2: A chibi-like special form and its subsequent sleeker upgrade, both of which are accessed from the Gashat, that grants levitation capabilities. These forms first appears in the crossover film Kamen Rider Heisei Generations: Dr. Pac-Man vs. Ex-Aid & Ghost with Legend Rider. Level 2: A special form accessed from the Gashat that grants the use of Kamen Rider Drive's Handle-Ken. This form appears exclusively in the web-exclusive special Kamen Rider Genm: Legend Rider Stage. Level 2: A special form accessed from the Gashat that grants the use of Kamen Rider Gaim's Daidaimaru. This form appears exclusively in the web-exclusive special Kamen Rider Genm: Legend Rider Stage. : A special form accessed from the Gashat that grants the ability to materialize weapons, obstacles, and traps. Emu's finisher in this form is an enhanced version of his original Critical Strike. This form appears exclusively in the film Kamen Rider Ex-Aid the Movie: True Ending. : A special form accessed from the Gashat that grants reality warping capabilities. Emu's finisher in this form is the . This form appears exclusively in the sequel novel Novel: Kamen Rider Ex-Aid: Mighty Novel X.
During the events of the crossover film Kamen Rider × Super Sentai: Ultra Super Hero Taisen, Emu temporarily assumes the form of Akarider where he commands the Gorengers' Variblune.
Emu Hojo is portrayed by . As a child, Emu is portrayed by .
Hiiro Kagami is a genius surgeon who recently returned from America, is described as a tsundere, displays a liking for sweets due to his late girlfriend Saki Momose, and can transform into . A prodigy in the medical field, Hiiro is initially passive-aggressive towards Emu due to their differing beliefs. However, the former slowly grows to respect the intern over time, even adopting some of his beliefs. Despite appearing callous, Hiiro does care for others.
During the first Zero Day incident, Momose was infected with the Bugster Virus, but she had kept it secret from Hiiro due to his aloof attitude until he eventually learned what had happened when Graphite manifested from her. When Taiga Hanaya fails to defeat the Bugster, Momose dies and Hiiro develops a grudge against Taiga and Graphite despite harboring guilty feelings for himself. With Emu's help, Hiiro eventually accepts that he had partially contributed to Momose's death and reconciles with him. Amidst the Kamen Rider Chronicle crisis, Hiiro discovers Momose is among the Bugster Virus-infected victims whose life forces are stored in the Proto-Gashats and is blackmailed into joining Masamune Dan, who threatens to delete her data unless Hiiro serves him. After remembering Momose's last words however, Hiiro rejoins CR to defeat Masamune, guide new interns, and make peace with his past.
During the events of the V-Cinema Kamen Rider Ex-Aid Trilogy: Another Ending, Hiiro reconciles with Taiga before joining forces with him to defeat Lovrica, who had brainwashed a temporarily resurrected Momose. Before she dies once more, Hiiro comes to terms with her first death.
Utilizing the Gashat in conjunction with the Gamer Driver, Hiiro can transform into Kamen Rider Brave Level 1. In this form, he wields the , can perform flaming dash attacks, and transform further into Quest Gamer Level 2. In both forms, he wields the , which can switch between and . Moreover, activating Taddle Quest generates a Game Area with several Energy Items randomly hidden inside treasure chest-like containers. He can also combine Taddle Quest with additional Gashats to achieve stronger forms, which are as follows: : An auxiliary form accessed from the Taddle Quest and Gashats that equips Hiiro with the right forearm-mounted phonograph and the left shoulder-mounted speaker. To compensate for his lack of experience in rhythm games, he incorporates CPR techniques into his attacks. : An auxiliary form accessed from the Taddle Quest and Drago Knight Hunter Z Gashats alongside up to three other Gamer Riders that equips Hiiro with the right forearm-mounted . : An enhanced version of Hunter Quest Gamer Level 5 (Dragon Blade) that equips Hiiro with the Drago Knight Fang and Gun. : A special form accessed from the Taddle Quest and Gashat that equips Hiiro with the baseball glove and the left shoulder-mounted pitching machine. This form appears exclusively in the web-exclusive special Kamen Rider Genm: Legend Gamer Stage. : A special form accessed from the Taddle Quest and Gashat that equips Hiiro with the sonokinetic helmet, the right forearm-mounted , and the left forearm-mounted . This form appears exclusively in the web-exclusive special Kamen Rider Brave: Survive! The Revived Beast Rider Squad. : A special form accessed from the Taddle Quest and Gashats that equips Hiiro with the chest-mounted laser cannon. This form appears exclusively in the crossover film Kamen Rider × Super Sentai: Ultra Super Hero Taisen.
Additionally, Hiiro can assume the following forms by using unique Gashats in place of Taddle Quest: : Hiiro's super form accessed from the Gashat Gear Dual β's mode that grants telekinesis, levitation capabilities, and the ability to open portals, create magical sword projections, and nullify the effects of Energy Items. His finisher in this form is the . : Hiiro's final form accessed from Another Hiiro's Taddle Legacy Gashat that grants the use of healing spells, which he can use on either himself or any of his allies, and the ability to create homing energy arrows. His finishers in this form are enhanced versions of his original Critical Strike and Finish, which increase in power if one of his allies is defeated in battle.
Hiiro Kagami is portrayed by .
Poppy Pipopapo is a Bugster based on a video game character from the fictional rhythm game DoReMiFa Beat who is able to assume a human guise called , works as a nurse for CR, and as a navigator for the Gamer Riders. She was born from Kuroto Dan's mother, , who had helped him during his youth before he infected her with the Bugster Virus in an attempt to save her from an unknown regular illness.