The Resurrection of Agul (アグル復活 Aguru Fukkatsu) is episode 41 of Ultraman Gaia. It features the first appearance of Agul V2.
A man is cowering inside a cave by the ocean, as the light hits his face Fujimiya screams...
Meanwhile on Aerial Base, XIG musters its forces as another wormhole opens up in the sky. Gamu notes that the power signature is similar to that of Zoruim, and Ishimuro assigns Team Crow to investigate. Gamu offers to go along, and is soon flying with Team Crow. A beam of gold metal particles drifts down to earth, materializing into the robot, Σ-Zuigul. Team Crow attacks, and Σ-Zuigul retaliates by shooting a missile which tracks Leader Inagi of Team Crow. Gamu transforms into Gaia, and takes out the missile, saving a relieved Inagi. He then engages Σ-Zuigul, attacking it until the robot shoots a special beam which flashes around Gaia's fists. Gaia appears to destroy Σ-Zuigul with a power flare. Team Crow returns to the Base, and Gaia is about to revert back to Gamu, when he spots Fujimiya stumbling towards the ocean.
Back as Gamu, he manages to stop Fujimiya from fully entering the ocean, which Fujimiya says was calling him. He then collapses, and Gamu helps him out of the water, taking him to a clinic. He discusses Fujimiya's condition with the professor, and while going to Fujimiya's room, notices weird black marks on the backs of both of his hands. He enters the room, and finds that Fujimiya has vanished.
Gamu finds him near the ocean, and Fujimiya mentions about some of the events that transpired since he reappeared, like the underground missile. They discuss the mistakes humans make, and the power of Ultraman, with Fujimiya admitting that Agul's power has not returned to him. He knows his relying on Crisis was wrong, and wants to make up for his mistakes. Gamu encourages him to keep fighting, as Senuma and one of his men arrive to take custody of Fujimiya. Gamu defends Fujimiya, much to the other's shock.
Just then, Σ-Zuigul recombines, and Gamu runs off to take care of him, asking Senuma to get Fujimiya out of harm's way. As Gamu runs towards Σ-Zuigul, the robot's sensors lock onto his form. Gamu tries to transform into Gaia, but then finds the Esplendor is covered with metal, as are the black marks on his hands. His arms are then forced out to the side, and a cross-shaped capsule forms around him. As he is struggling to escape his new prison, Σ-Zuigul draws the capsule into its chest.
Team Lightning and Peace Carry arrive, and Tsutsumi orders the planes to start attacking the robot. Leader Kajio starts calling out attack plans, when Kitada interrupts him, directing everyone's attention to Gamu being held hostage. Ishimuro figures out that this was the reason why this particular weapon was used. With no other choice, Team Lightning breaks off the attack.
Fujimiya, still being led away, senses Gamu's predicament, and breaks away from the two men. They try to follow him, but the wormhole opening stops them. Fujimiya runs toward Σ-Zuigul, who knocks him out with a laser attack. Kajio demands to attack, but Tsutsumi replies they might endanger Gamu. With the rest of the XIG team watching helplessly, and with no other interferences, Σ-Zuigul lifts off to return into the wormhole with its still-struggling hostage.
Fujimiya mentions Gamu's name, and hearing him mentally, Gamu screams out Fujimiya's name as the robot nears the wormhole. Fujimiya has flashes of Gamu, Reiko, and Inamori calling out to him, with scenes of humanity, including Yuki(whom he had saved in episode 20), the boy who had drawn the picture of Gaia and Agul in the hospital, and a baby. Remembering words Gamu had told him earlier, he resolves to fight once more, and calls upon the earth to once more give him the power of Agul. Time seems to stop, and he scrambles to his feet as a huge wave approaches the shoreline, bearing with it the blue light of Agul. As the wave engulfs him, he transforms into Agul V2, and flies up to stop the robot from entering the wormhole.
As they travel back down to earth, Agul tries to shield Gamu from too much damage as they crash back on the ground. He tries to punch Σ-Zuigul, but the robot presents its chest with Gamu inside, stopping Agul from attacking. It tries to lift off once more, but Agul kicks one of the flight-arms off, preventing its escape. Agul forms his blade and carves around the capsule. He draws the capsule out and plants it onto the ground, where Senuma and his associate rescue Gamu from it. They watch as Agul fights Σ-Zuigul, who is unable to keep up its powerful attacks due to Agul carving out the robot's chest, and it isn't long before Agul shoots a beam through Σ-Zuigul, destroying it.
Agul reverts to Fujimiya, who watches Gamu take off in his jet. As Gamu notes his hands are free of Σ-Zuigul's marks, he is ordered back to XIG, and mentally addresses Fujimiya, each holding up their respective transform devices to show the lights within.