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Icon-exaid.png This article is about a villain in Kamen Rider Ex-Aid and Kamen Rider Ghost. Icon-ghost.png

Michihiko Zaizen (財前 美智彦, Zaizen Michihiko) is the main antagonist of Kamen Rider Heisei Generations: Dr. Pac-Man vs. Ex-Aid & Ghost with Legend Riders. He was the leader of Next Genome Institute who brought forth a new strain of the Bugster Virus as Dr. Pac-Man (DR.パックマン, Dokutā Pakkuman). After having the Hatena Bugster rewrite his genetics, he mutated into a combination of Bugster and human, known as the Genomes (ゲノムス, Genomusu).



Michihiko Zaizen is head scientist of the Next Genome Institute. Six years ago, Zaizen along with Soji Kuruse, Kazushige Ryuzaki, and Ageha Takeda were hired by Kuroto Dan to extract the Bugster virus from Emu Hojo's body. However, a large amount of the Bugster virus was released, infecting the surgeons and causing them to vanish. They were declared missing, but unbeknowst to everyone, their data was trapped in the Game World.

Heisei Generations: Dr. Pac-Man vs. Ex-Aid & Ghost with Legend Riders

Michihiko Zaizen and his associates would eventually be revived as Bugsters in present day. Assuming the identity as "Dr. Pac-Man, Zaizen attacked Genm Corp. and seizes the Gashacon Bugvisor and Proto Gashats from Kuroto Dan. He created the Pac-Man Virus to locate the strain of a new type of Bugster virus, which is found within Togo Kiyomiya. The virus from Togo spawned into the Hatena Bugster. Using the Hatena Bugster's power to rewrite his DNA, Zaizen evolved himself into a more powerful Bugster known as the Genomes.

He attempted to evolve Togo into a similar being and had planned to mass produce the treatment once the experiment was complete. However, the Next Genome Institute would be intercepted by the Kamen Riders. Recognizing Ex-Aid as the Patient Zero of the Bugster Virus he operated on years ago, he tries to erase him using the Proto Mighty Action X Gashat, only giving advent to Ex-Aid Double Action Gamer Level XX. Genomes would ultimately be vanquished by Ex-Aid Level XX's Critical Strike.


"Dr. Pac-Man" returns, holding three legendary Gashats.

Following Zaizen's downfall, the alias of "Dr. Pac-Man" would be taken by Parado as he interrupted Kamen Rider Genm's own plot to utilize the Ganbarizing Gashat. Parado provided Bandai Namco-based Gashats to the Doctor Riders, before the Gashats were retrieved back for Genm.

Taiga Hanaya would learn of Emu Hojo's true nature as Patient Zero of the Bugster Virus after Kuroto Dan confirmed Michihiko Zaizen had performed his surgery to extract the virus six years ago. What Kuroto neglected to mention is that he himself who first gave Emu the Bugster Virus a further decade prior, and that Zaizen merely extracted the cultivated virus, later revealed to be Parado.

Returned as data copy by his own daughter.

It would be revealed that Michihiko Zaizen had a daughter named Saiko Yaotome, whom he lost custody after his wife divorced him. Saiko desired revenge on the Kamen Riders for taking her father away from him, working together with Kuroto Dan to fulfill her goals. Zaizen's data was later used by Saiko to reproduce a copy of Genomes in order to battle with Another Parado against Kamen Riders Para-DX and Poppy, but was ultimately vanquished once more.


to be added

Powers and Abilities

In Pac Man form Zaizen was capable of jumping around and firing yellow energy needles from his mouth. In Genomes form he had his Gashacon Bugvisor mounted on his right wrist and could fire blue lasers from his body.



  • Height: 206.7 cm[1]
  • Weight: 115.5 kg[1]

Appearances: Heisei Generations, Para-DX with Poppy


Behind the Scenes


Michihiko Zaizen & Dr. Pac-Man was portrayed by Shiro Sano (佐野 史郎, Sano Shiro), who previously played Weeval/Makuu Prison Warden AshuradaIcon-crosswiki.png in Kaizoku Sentai Gokaiger vs. Uchuu Keiji Gavan: The MovieIcon-crosswiki.png. As Genomes, his suit actor is unknown.

Concept Art

Genomes concept art

Genomes was designed by Niθ (ニシー, Nishī).


  • Michihiko Zaizen is the third character who uses the Gashacon Bugvisor, and the second Bugster to use it as a weapon.
  • Unlike Graphite and Lovelica, he doesn't use it to transform, but still uses it for its other functions, including infecting his targets like Graphite did.
  • Genomes is designed by Niθ.





Icon-exaid.png Kamen Rider Ex-Aid
Kamen Riders
Emu Hojo - Hiiro Kagami (Game World) - Taiga Hanaya - Kiriya Kujo - Kuroto Dan - Parado - Asuna Karino/Poppy Pipopapo - Masamune Dan - Ride-Players (Nico Saiba - Haima Kagami) - Genm (Bakusou Treasure) - Kagenari Nagumo - Ninja-Player - Black Parado
Game Scope - Gamer Driver - Kimewaza Slot Holder - Rider Gashat - Energy Items - Buggle Driver (II) - Bugster Buckle - Gashat Gear Dual (β - Another) - Rider Gauges - Rider Gashat Case - Energy Item Holder
Gashacon Weapons
Gashacon Breaker - Gashacon Sword - Gashacon Magnum - Gashacon Sparrow - Gashacon Bugvisor (II - G) - Gashacon Key Slasher - Gashacon Parabragun
Other Weapons
Flamber Saber - Ride Weapon - Fuma Sōzantō - Genin Weapon
Robot Gamer - Beat Gamer - Combat Gamer - Chambara Gamer - Sports Gamer - Hunter Gamer - Bike Gamer - Burger Gamer - Fantasy Gamer - Simulation Gamer - Maximum Gamer - Safari Gamer - Tank Gamer - Legacy Gamer - Pac Gamer - Famista Gamer - Xevious Gamer - Galaxian Gamer
Asuna Karino - Haima Kagami - Kyotaro Hinata - Ginko Yumita - Nico Saiba - Satsuki Ogimachi - Mizuki Nishikikoji - Tsukuru Koboshi
Others: Saki Momose - Sakurako Dan - Eight Kirino - Saiko Yaotome
Locations: Seito University Hospital - CR - Ministry of Health - Hanaya Game Illness Clinic - Genm Corp. - Game World - Machina Vision - Next Genome Institute
Generals: Parado - Graphite - Ren Amagasaki - Gamedeus
Movie-exclusive: Michihiko Zaizen - Pac-Man Virus - Hatena Bugster - Soji Kuruse - Kazushige Ryuzaki - Ageha Takeda - Johnny Makishima - Nebula Bugster
Stageshow-exlusive: Futago Bugster
Regular Bugsters: Bugster Virus - Bugster Union - Salty Bugster - Aranbura Bugster - Revol Bugster - Motors Bugster - Collabos Bugsters (Gekitotsu - DoReMiFa - Giri Giri - Jet - Kamen Rider Genm series) - Burgermon Bugster - Gatton Bugster - Vernier Bugster - Kaiden Bugster - Charlie Bugster
Regular Games: Mighty Action X - Taddle Quest - Bang Bang Shooting - Bakusou Bike - Gekitotsu Robots - DoReMiFa Beat - Giri Giri Chambara - Jet Combat - Shakariki Sports - Drago Knight Hunter Z - Dangerous Zombie - Mighty Brothers XX - Perfect Puzzle - Knock Out Fighter - Perfect Knock Out - Ju Ju Burger - Night of Safari - Bang Bang Tank - Taddle Fantasy - Bang Bang Simulations - Taddle Legacy - Maximum Mighty X - Kamen Rider Chronicle - Toki Meki Crisis - Hyper Muteki - Doctor Mighty XX - Mighty Creator VRX - Hurricane Ninja - God Maximum Mighty X - Knock Out Fighter 2 - Zombie Chronicle - Mighty Novel X - Genm Musou
Legend Rider Games: Let's Go Ichi Gou! - Adventure Guy Kuuga - Agito of the Sun - Mirror Labyrinth Ryuki - Moshi Moshi Faiz - King of Poker Blade - Taiko Master Hibiki - Insect Wars Kabuto - Time Express Den-O - DokiDoki Makai Castle Kiva - Barcode Warrior Decade - Detective Double - Jungle OOO - Space Galaxy Fourze - Magic The Wizard - Toukenden Gaim - Full Throttle Drive - Kaigan Ghost - Kamen Rider Build - Ganbarizing
Legend Games: Pac Adventure - Famista - Xevious - Taiko no Tatsujin - Galaxian
Other Games: Hatesate Puzzle - Buddhist Priest of Temple - Chou Super Hero Taisen - Chou Shocker Taisen - Bakusou Treasure - WayoseTUNE - Nazo Toki Labyrinth