As Mamoru destroys the Master Program, Guy is glad that they no longer have to rely on THE POWER because nobody is able to control it and inwardly thanks all those who helped them reach this point. Later, he checks on the bedridden Mikoto and carries her to a view screen where they see the Earth. 3G cheerfully looks forward to getting back home and enjoying real food. The Earth broadcasts 3G’s triumphant return and hails them as heroes. Mic drops Mamoru off at his home and his parents welcome him with open arms. Later, he watches a sunset with Hana. Back in 3G’s hangar, Mic refuses to go through an overhaul because he wants to play with Mamoru. RaiRyu agrees but HyoRyu reminds them that they must always be prepared. As they reminiscence about fighting the Machine Kings and the Primevals, Goldymarg boasts about getting the most kills but Mic reminds him that it’s Guy who always delivers the killing blow and the two start bickering. On Earth, 3G visits the Shishioh family grave and Liger places Leo’s rocket skates on it, complaining that his brother just had to go before him. Guy promises his parents that he’ll visit them at Jupiter one day. Guy and Mikoto excuse themselves to go pay respect to Mikoto’s parents. Mamoru wants to come along but Hyuuma stops him so the two can have some time alone. Mikoto remembers EI-01’s landing from three years ago which caused the death of her parents, and Guy says the nightmare is finally over. They spot the Galeorea comet which comes around every eight years and Mikoto reminds him that he mentioned his dream to become an astronaut the last time they saw the comet. Guy remembers Mikoto’s pendant and thanks her for all her help, but Mikoto says that he was the one who gave her the courage to go on. With the world finally at peace, she gives him the letter she was hiding all these years and says that she’ll always be by his side before suddenly fainting.
On the Orbit Base, Guy tells the bedridden Mikoto that she was probably just exhausted and the two hold hands. Mamoru goes over the family photo album with his parents and reminiscence about the trips they had, hoping that they won’t get interrupted by Zonders next time. Mamoru thanks his parents and bids them good night. The next day he goes with his class on a field trip to city hall. His friends discuss the events that happened throughout the year as they see the city being rebuilt. Hana notes that they haven’t seen Kaidou since the Tokyo upheaval. She reminds Mamoru of their promise and their friends jokingly tell them to get married now. Mamoru suddenly has a bad feeling. Mikoto starts suffering convulsions and grabs Guy’s hand, draining him of his energy. Mikoto then transforms into the new machine species Zonuda and starts draining all the energy from around her. 3G is puzzled about the cause of this, and Swan and Kazou report drastic power drops wherever Mikoto goes. Entouji tracks her to the hangar in Amaterasu, where she has managed to disable the Brave Robot Corps. Guy shows up and manages to trap her on one side of the ship but she separates the entire half and pilots it towards Earth. It crashes into Tokyo and Mikoto turns the wreckage into a Zonuda robo which begins mechanizing anything it touches. Mamoru wonders what it is since it’s neither Zonder nor Primeval. As the Zonuda robo approaches city hall, the civilians panic and start evacuating en masse. Suddenly Galeon comes roaring down and Mamoru vainly tells him to stay away.
Poor 3G just never seems to catch a break. You’d think this would have been a simple clip show and epilogue episode to tie up loose ends but out pops yet another threat. It’s not out of the blue though, since it’s been hinted for quite a while that there was something wrong with Mikoto. Up against a monster with ability to instantly mechanize anything and with only a sliver of their power, 3G has their work cut out for them. On lighter note, we get cameos by some of the former Zonder victims during 3G’s return to Earth.