The Zambird and Zambull fly across the ocean and split up, searching for an enemy while Keiko is patrolling in the Zambase underwater. Heizaemon contacts the other Beal ships and they combine into the King Beal. Uchuta and Keiko’s parents come aboard to see Heizaemon, who says they need to find where the Gaizock create the human bombs. The Bandock is currently hiding underwater where Killer the Butcher is playing and singing about being a murderer. Gizarr tells Killer about the actions of the Jin family and tells him of a plan. Butcher starts singing again. Many captives are dragged throughout the ship including Kouzuki, who is put into a cell where Michi is. He asks where Yamada is but she says she hasn’t seen him. He says he is going to pay a debt to Kappei and asks her about Aki, who Michi says was taken away with some other people. Kouzuki remembers seeing Aki in a crowd with many other people being led to a room with a blinking red light. Kouzuki realizes she is being converted into a human bomb. He tries to break out of the room to no avail. Meanwhile Kappei continues to patrol and spots the Mecha Boost Kuragen approaching. The Kuragen blows up a boat on the ocean. Ichitaro says he’ll contact the others and to not go too far off on his own. Kappei ignores him and fires at the Kuragen, which shoots some tentacles that wrap about the Zambird and force it into the water. The Zambird breaks free but the Kuragen has gotten away. Kappei sees Aki in the water, a survivor from the boat, holding onto some wreckage. He changes into the Zambo Ace and she climbs aboard, inside the foot. Heizaemon thinks something is strange since the Mecha Boost ran away so easily. Uchuta tries to rescue some of the survivors but Heizaemon says not too, since they could be human bombs. He doesn’t want any of them to be brought on board. He wonders what Kappei is doing. At that time Kappei has brought Aki aboard the ship. She says she doesn’t remember anything outside of being captured by the Gaizock. Kappei lets her into his room. Kappei tells her she can stay here and he’ll convince his Heizaemon to let her stay. Kappei tosses her something to wear and leaves to let her get changed, being embarrassed. He tries to sneak a look back in and she bangs him in the head with his helmet. Kappei tells Heizaemon he let her on board and he angrily tells him to get rid of her since she could be a human bomb. Kappei doesn’t believe it. In Kappei’s room we see a star tattoo on Aki’s back. Meanwhile on the Bandock Butcher drinks and comments on the bad habit of humans helping each other. Kappei grows angry, not believing Aki has turned into a human bomb. He rushes to his room, where she is reading. Aki explodes moments before he gets there. Heizaemon orders shutters lowered to seal off the wreckage. Kappei runs to the deck where smoke emanates from the King Beal due to the explosion. A piece of clothing from the coat Kappei gave Aki floats into his hands and he starts crying, also getting angry.
The Kuragen approaches and Kappei gets back in the Zambo Ace. Kappei repeatedly shoots at it but it swipes away any bullets with its tentacles. The Zambase and Zambull arrive and fire at the Kuragen, enabling the Zambo Ace to break free. The Kuragen launches more attacks on the King Beal and Kappei fires at it, blowing tentacles off of the top of it. The Kuragen starts spinning and flies towards the Zambo Ace. Kappei tells Uchuta to fire a missile towards him, which Kappei does. The Zambo Ace grabs the missile and throws it into the face of the Kuragen, destroying it. Heizaemon asks Keiko where the Mecha Boost came from and she said it came from the ocean, so Heizaemon tells them to combine and search the ocean for the Gaizock. The three crafts combine into the Zambot 3. The Zambot Ace heads underwater and is being watched by Killer the Butcher who tells Gizarr to not let the enemy get close to the Bandock. Kouzuki asks a guard who blew up and the guard says she was near the age of Michi, making them realize it was Aki. Kouzuki and Michi cry over Aki’s death. The head of the Bandock launches off of the craft, ascending through the water. The Zambot 3 approaches the maximum water pressure it can handle. Kappei remembers playing with Aki and Michi. Kappei, still sobbing wonders why she was born, suffering such a fate. The Bandock‘s head fires a missile at the Zambot which dodges it. Kappei angrily says he’ll avenge Aki’s death, saying he doesn’t care if the Zambot is broken as a result. The Zambot dodges additional missiles fires by the Bandock and throws the Zambot cutter at it, but the water causes it to drift away. Another missile is launches at him. Some prisoners are moved out of Kouzuki’s cell and he runs out, knocking them out. He kills two more guards and runs off with Michi behind him. They make their way to another chamber and fire upon some more guards, finding a submarine-type device that Michi gets in. Kouzuki tells her to tell Kappei that he’ll shake his hand if they ever see each other again. He launches the craft, which takes off. Meanwhile the Zambot continues to fight the Bandock‘s head, launching its moon attack, but the attack has no effect. Gizarr laughs from aboard the craft and says to drag the Zambot further below so they can crush it with the water pressure. Heizaemon tells Kappei to retreat and the Zambot’s controls start malfunctioning due to the equipment. Kappei tells Aki to forgive him and ascends out of the water. The submarine craft with Michi appears from out of the water. Kappei’s grandmother asks to inspect her back with a camera and she shows that it is bare so they can let her on. Kappei gets off and Michi starts crying, telling her Aki was killed. Kappei is surprised to hear she was inside the Bandock and was helped escape by Kouzuki. She tells him Kouzuki wanted to pay a debt to him. She is worried that he will die in there and gives Kappei his message about shaking his hand if they see each other again. Kappei’s father pulls out the room that Aki blew up in with a crane and releases it into the water. Kappei watches as it sinks below the water.
Another fairly good episode, with another character biting the dust, this time Kappei’s friend Aki. While the romantic angle kind of came a bit out of nowhere (they seemed friends, but not that good friends), it made sense to pull this off with a more established character than those who perished in the previous episode. Kappei gets very emotional here and it almost costs him and the others their lives. The Kuragen was another interesting design for the Mecha Boost. The scenes with Killer the Butcher playing in a band and singing come off as quite childish and goofy though in contrast with the much more serious tone of everything else here, even if he was singing about murdering people.