Nostalgic Children is the thirty-ninth episode of Engine Sentai Go-Onger.
Kitaneidas uses Yatai Banki to capture children in his Festival Space on a daily basis across the city before expanding it worldwide. After hearing eyewitness accounts of the children disappearing from friends and siblings, Gunpei and Hant are bewitched by their own childhood memories as they end up getting trapped in the Festival Space themselves. It is there the two meet a pair of brothers named Harunosuke and Akinosuke as Yatai Banki reveals himself to attack them. But Kishamoth breaks the space, with the Go-on teams fighting Yatai Banki as the brothers run into Kishamoth and drive off with him as Gunpei and Hant get it. As Yatai Banki escapes, Gunpei and Hant learn the brothers are from the Samurai World as Kishamoth reverts to Engine Cast and Engine Soul. Meanwhile at Hellgailles Palace, the Gaiark Ministers are visited by a familiar pair of Yōma who ask them to get the two brothers and the sword the young brother carries. While Gunpei notices the sword on Akinosuke's back, the brothers run off as the two try to come after them. But Yatai Banki blocks their way at the two are forced to fight him as the others arrive while the Gaiark Ministers trick the brothers into trusting them. But when they see through the Ministers' deception at the last minute, the brothers run back to the Go-ongers and return Kishamoth's Engine Soul as Go-on Red gives Go-on Green and Go-on Black the Kankanbar to defeat Yatai Banki and free the children. When Yatai Banki Industrial Revolutionizes, he traps Engine-Oh and Seiku-Oh in Festival Space games as GunBir-Oh frees them and three beat him senselessly before scrapping him. As Harunosuke apologizes for his distrust, he reveals the sword Akinosuke carries to belong to the Go-ongers' old friend Retsu-Taka, as Engine Dai-Shogun lands in the middle of the city still in its petrified state.