Water Pollution Minister Kegalesia sends Pipe Banki to pollute Earth's waters. Bomper, the Go-onger's support robo, picks up on Pipe Banki's presence and sends the three Go-ongers to the nearby dam to battle Pipe Banki and the Ugatz. Surprisingly, Pipe Banki escapes before the battle's end, satisfied with how his powers have affected the water supply. During the fight, Gunpei sneaks aboard the Ginjiro-go, kidnaps Bomper, and steals the Engine Casts. Again, he demands information about the Go-ongers and threatens to disassemble the frightened robo. Hant appears and is awed by Bomper's ability to speak. After Bomper tells Gunpei and Hant why the Engines need human partners, the Go-ongers arrive. S?suke struggles with Gunpei to retrieve the Engine Casts, but Gunpei easily shoves him away. Once again, Gunpei questions the Go-ongers' maturity and battle-worthiness and refuses to return the Engine Casts. Suddenly, Bomper reports that an Industrial Revolutionized Pipe Banki has arrived to flood the city. Without their Engine Casts, the Go-ongers assemble the Highway Buster in a seemingly futile attempt to defeat Pipe Banki. As Gunpei watches them recklessly fight against the odds, Bomper reveals the origins of the three Go-ongers and why they were picked as the Engines' drivers. With a change of heart, Gunpei decides to return the Engine Casts, and Hant offers his help to do so. Seeing the same sense of justice he saw in S?suke, Renn, and Saki, Bomper gives Hant and Gunpei the ShiftChangers, allowing them to become Go-ongers. With their Engine Casts back, the primary Go-ongers are able to form Engine-Oh to battle Pipe Banki. During the fight, a bridge span is destroyed, which endangers an innocent woman and child trapped in their car. Engine-Oh is unable to land the deathblow on Pipe Banki until Go-on Green and Go-on Black rescue mother and son. With the addition of Hant and Gunpei, the Go-ongers are finally assembled to fight Gaiark.[2]