Originally released in 2007, the 13-episode ULTRA GALAXY: MEGA MONSTER BATTLE was linked to a popular Japanese arcade card game in which monsters from across the Ultraman Series engaged in head-to-head combat. The show is set in the distant future, as the Earth organization ZAP SPACY explores unknown planets for much-needed natural resources. Under the leadership of Captain Hyuga, the crew of the spaceship Pendragon crash-land on Planet Boris, a desolate world teaming with warring giant monsters. There they encounter a mysterious young man named Rei who uses a device called the Battlenizer to summon and control his own monsters.

The story continues in the 2008 sequel series ULTRA GALAXY: MEGA MONSTER BATTLE NEVER ENDING ODYSSEY. The Pendragon team are attacked by the Reionics Hunters, members of the alien Pedan race that seek to exterminate all of Rei's kind. The conflict leads the crew to the monster-filled Planet Hammer and an encounter with Alien Reiblood, first of the Reionics.

Rei and the Pendragon crew return in the 2009 theatrical feature MEGA MONSTER BATTLE ULTRA GALAXY THE MOVIE, a special effects extravaganza with nearly all of the Ultra Heroes! A terrifying threat returns to destroy the Ultraman homeworld, the Land of Light in Nebula M78, when the evil Ultraman Belial is released from centuries of imprisonment. Armed with a powerful Reionics weapon called the Giga Battlenizer, Bellial defeats one Ultraman after another and steals the Plasma Spark, the energy source for the Land of Light. Ultraman Mebius seeks out Rei to help rescue Ultraman and Ultraseven and recover the Plasma Spark. But will even the timely assistance of Ultraman Dyna and the powerful young fighter Ultraman Zero be enough to turn the tide against Belial and his army of monsters?