Ultra Galaxy Mega Monster Battle: Never Ending Odyssey (ウルトラギャラクシー大怪獣バトル NEVER ENDING ODYSSEY,Urutora Gyarakushī Daikaijū Batoru Nebā Endingu Odessei) is a Japanese tokusatsu drama in Tsuburaya's Ultra Series and a direct sequel to Ultra Galaxy Mega Monster Battle. Together with its prequel and movie, they are the 23rd series overall. This series started on December 20, 2008.
Taking place shortly after the events of Ultra Galaxy Mega Monster Battle, the ZAP SPACY comes under attack by a mysterious man known as the "Reionyx Hunter," who soon reveals himself as "Dail," an Alien Pedan from the future who has traveled back in time to seek out and exterminate all Reionyxs in the universe. After Dail attempts to kill Rei on a ZAP Space Station, Rei and Captain Hyuga are separated from the other ZAP teammates and transported to Planet Hammer, where they learn that Reionyxs from all over the universe are gathering to battle each other to inherit the latent powers of the thought-to-be-dead Alien Reiblood, who is sealed deep within the planet himself.
To make matters worse, Rei must come to accept his new Reiblood heritage, as well as learn how to control his aggressive latent instincts when he gets corrupted by them. Together, he and the ZAP SPACY must fend off the hostile Reibloods on Planet Hammer, as well as unravel the mysteries to the Alien Pedan's true intentions, Rei's additional latent abilities after he is challenged by another Reibloodwith a unique Batle Nizer, as well as unknown visions that he is having of another giant on the planet.
Like the previous series, a segment that the end of the episode known as "Mega Monster Battle File" features Oki and Kumano showcasing the Monsters of their respective episodes being displayed while tidbits of the Monsters are explained as well as Oki and Kumano's personal experiences with the Monsters.