Bugster Virus

The Bugster Virus are the foot soldiers of the Bugsters in Kamen Rider Ex-Aid.

The Bugster Virus initially start off as a micro-sized virus infecting humans. Bugster-infected may either show symptoms akin to normal human illnesses, or even show no symptoms at all. The Bugster Virus begins to develop inside an infected human as they begin to get stressed out, until the human is physically taken over and covered by the virus, transforming them into a gigantic virus-like Bugster Union.

Once a Kamen Rider in a Level 1 form extracts the virus from its human host by defeating the Union, the human host is released, while the extracted virus becomes a person-sized Bugster monster accompanied by a few Bugster Virus foot soldiers. The human host's body will gradually become transparent until he or she is "treated" by destroying the Bugster monster and the Bugster Viruses. If the Riders fail to defeat the Bugster monster and the Bugster Viruses fast enough, the human host will disappear completely (this is shown by Saki Momose when Taiga fails to defeat Graphite). This process can be sped up by causing the host additional stress. A similar case if the Riders fail to defeat the Bugsters who are at Level 30 or above, the Bugsters will instead completely taking over their hosts' body while destroying their hosts' mind as well.

It appears that some games, like Bakusou Bike, also employ neutral Bugster Viruses.

Large-sized versions of Bugster Virus cells are seen in the Mighty Action X game as enemies that Mighty faces.

It was first discovered by Kuroto Dan back in 2000, the same year where the future Kamen Rider Ex-Aid, Emu Hojo had a special surgery led by Kyotaro Hinata when they were still young.

Concluding a series of tests he was made to undergo at CR after discovering the Bugster Virus, Taiga Hanaya was entered into a VR simulation by Poppy Pipopapo on Kuroto Dan's order. Provided with the Gashacon Magnum, Taiga was faced with a succession of five Bugster Virus grunts whom he expertly terminated due to his experience in radiology, proving himself to be an ideal candidate for Kamen Rider Snipe.

A group of Bugster Viruses form with the Salty Bugster from small viruses that jumped off of Sota's giant virus form, many of them taking on chef/cook costumes. They fight against Kamen Rider Ex-Aid Action Gamer Level 2, but are quickly destroyed by the Gashacon Breaker.

A single Bugster Virus faced Emu Hojo in a virtual reality simulation conducted by Kuroto Dan to record his specs in the Action Gamer. Guided by Poppy Pipopapo into transforming first to Level 1 then to Level 2, Ex-Aid was finally instructed to activate his Critical Strike finisher using the Kimewaza Slot Holder, ending the simulation as he terminate the Bugster Virus.

A group of Bugster Viruses form with the Aranbura Bugster after Rensuke's giant virus form is defeated, some of them taking on the same cook costumes as Salty's followers, but many becoming hooded monks; they escape the scene after Kamen Rider Genm's interference. The regular and monk Viruses later fight and are defeated by Ex-Aid and Brave and their Gashacon Breaker and Sword (the cook Viruses presumably changed costume prior to this).

The Revol Bugster summons a group of Viruses when confronted by the Kamen Riders. Because of Yuki Kitami's high stress level, it can continue to summon more and more Viruses as the Riders defeat those present, even being able to turn them into copies of itself. However, when Yuki recovers from his stress, it loses the ability to summon more, and it is revealed that the Revol Bugster summoning the Viruses was itself a Virus copy of the real original a split second before it is destroyed.

Likewise, a Bugster Virus was faced by Taiga Hanaya in a virtual reality simulation of the Shooting Gamer he blackmailed Dan to conduct. After transforming himself, Snipe too performed his Critical Strike to finish the Bugster Virus.

One Bugster Virus becomes the Motors Bugster's motorcycle, the Motors Viper. Another is seemingly summoned by the Bakusou Bike Gashat, acting as the race's checkered flag waver, and does not need to be fought and defeated to achieve a Game Clear.

A pack of Bugster Viruses manifested to advance on Ayumu, the mysterious boy who carried the Shakiri Sports Gashat. Moving to defend the boy, Takeru Tenkuji engaged the Bugsters as Kamen Rider Ghost before being joined by Kamen Rider Ex-Aid as the Viruses were soon enough destroyed by the two Kamen Riders. After the Gashat was swiped by Kamen Rider Genm, a second pack of Bugster Viruses appeared but were quickly destroyed by the two Riders, with Ghost performing his Omega Drive Rider Kick while Ex-Aid utilized his Gashacon Breaker.

The DoReMiFa Collabos Bugster summons a group of Bugster Viruses dressed as street dancers in hoodies and jeans to fight Ex-Aid and Brave. They are eventually defeated by the Beat Gamer's Sound Trap Attack.

A cloud of black-colored microscopic Bugster Viruses are released from the Proto Drago Knight Hunter Z Gashat by Graphite to infect Deputy Director-General Hinata and others. The Bugster Union released from Hinata's infection behaves differently from any other before, separating from his body instead of taking him over.

Countless Bugster Viruses made up the vast majority of a perpetually reviving army of Bugsters which emerged in the real world as a result of Kuroto Dan's plot to revive in the Game World. This endless horde was held off by Kamen Riders Brave and Snipe, sharing the Gashat Gear Dual β and Hunter Gamer between each other, while Emu was sent from CR to the Game World to stop Dan. Ultimately, the Bugster horde was suddenly dissipated in an instant as the destruction of the Game World brought about by Kazuma Kenzaki thwarted Dan's ambition to revive.

Arsenals

 * Tridents: By default, Bugster Viruses without costumes are armed with trident weapons.
 * Costume-themed Weapons: When they take on a costume, they become armed with weapons/tools/objects relevant to their costume.
 * As Japanese monks, the Bugster Viruses wield wooden rods.
 * As chefs/cooks, the Salty Bugster's Bugster Viruses wield whisks, large metal bowls, and/or staff-sized wooden spoons.
 * As hooded monks, the Aranbura Bugster's Bugster Viruses wield mace staffs.
 * As soldiers, the Revol Bugster's Bugster Viruses wield military guns.
 * The Motors Bugster's Virus takes the form of a motorcycle with a Virus head mounted in front of the handlebars.
 * The flagman Bugster Virus from the Bakusou Bike game holds a checkered flag.
 * As baseball players, the Famista Bugster Viruses wield baseball equipment.
 * As Gamma Commandos, the Ghost Bugster's Bugster Viruses wield short blade weapons.

Trivia

 * TBA