|Home world:||Planet Earth|
|First appearance:||Ultraman Tiga episode 2 "Stone Legends"|
|Affiliation:||Beryudora (Body part)|
Subtitle: Rock Monster (岩石怪獣, Ganseki Kaijū?)
Alpha The Gakumas were monsters that have lived underground for years, happily eating rock. However, once their home was disturbed by a construction crew who began to take their rock away, the monsters began to rampage to drive off their invaders. The first was Gakuma Alpha who surfaced and attacked the crew, solidifying everyone and everything in sight with its Stone Beam. GUTS arrived on the scene just as Gakuma Alpha was attacking, and using its new weapon: the DEXUS beam, Gakuma Alpha was destroyed in one shot.
BetaA short time later, Gakuma Beta then surfaced and picked up where its younger brother had left off, solidifying anything it saw, until it turned its attention to GUTS. Daigo was able to turn into Ultraman Tiga just in time and the two battled. Gakuma Beta's extra array of weapons proved too much for Tiga to handle, and the Ultra was quickly put in a fix when the Gakuma fired its stone beam at the Ultra, slowly solidifying him. Fortunately, the rock coating was destroyed once Tiga transformed into Power Type. The tide of battle turned in Tiga's favor, and he attacked Gakuma Beta until the monster was destroyed by Tiga's Delacium Light Stream.
- Suit Actors: Hiroyuki Okano (Alpha) and Toshio Miyake (Beta)
- It is assumed both Gakumas can use the same powers.
- The Gakumas shares the same subtitle as Sadora.
- Gakuma roars are actually heavily modified elephant trumpets.
- Although not physically seen, one of the Gakumas is one of the monsters that makes up Beryudora's Right Arm in Mega Monster Battle: Ultra Galaxy Legend The Movie.
- Gakuma Alpha is the first monster defeated by GUTS without Ultraman Tiga's assistance.
- The costume for Gakuma Beta is currently on display at Ultraman Land in Kumamoto, Japan.
- Gakuma resembles Zambolar