S y n o p s i s

At the end of the Dark Spark War, a huge amount of Dark Energy has spread out to the whole universe. Thus, the dark antagonist of Ultra Brothers: Dark Killer and several dark entities resurrect from the Monster Graveyard. They established the League of Darkness on Planet Tenebris.
The League of Darkness attack the New Generation Heroes in different planets. With Grigio and Zero in their captivity, they used them as leverage to lure the young Ultras to Planet Tenebris, aiming to duplicate them by absorbing and transferring their light energy to darkness, as part of the great mystical evil plan.
Therefore, the commander of Galactic Defense Force, Ultraman Taro, arranges their first assembly for a counterattack in the Battle of Tenebris. Lately, it was clear that his former comrade Tregear was playing behind the scenes.