The 15-minute short film, Sea Jetter Kaito featuring Yuki Satoh (Kamen Rider Gattack) and Seiji Takaiwa, recently premiered at the Ishinomori Manga Museum. 

Koushin Narumi (Seiji Takaiwa) transforms into Sea Jetter Kaito and fights Crababyssis along with some Myuganoid grunts. He quickly defeats the Myuganoids. As he fights Crababyssis, the mysterious Pharynx appears and joins the fight. The fight reaches a stalemate and the credits roll, with a “To be continued” text on the screen.

It is then revealed that Ichiro (Yuki Satoh) went to the Ishinomori Manga Museum with his son, Daichi, to watch the short film “Fight! Sea Jetter Kaito”
Ichiro tells his son that Sea Jetter Kaito actually exists in real life. When he was a child, he was attacked by Myuganoids while protecting a fish, until Kaito came to the rescue. Kaito takes out a red orb, which slowly heals the fish. Kaito is deeply moved by Ichiro’s actions and calls him an ally of justice by giving him a red orb. But Daichi quickly dismisses his father’s story by saying it was probably just a dream. Daichi goes to the toilet and as he’s about to wash his hands, a green liquid pours out the faucet. Crababyssis emerges and kidnaps Daichi, saying that he’s the perfect sacrifice for Octanol the God of Destruction.

As Ichiro is waiting for his son, he plans on giving Daichi the red orb when Daichi learns to love heroes. He says Crababyssis and quickly chases after the monster. They both arrive at the nearby beach, where Jakuabyssis is waiting for his partner Crababyssis.
The red orb changes into a belt from Ichiro’s wish to save his son. Ichiro yells “Brandishing Steel” (senkou) and transforms into Sea Jetter Kaito.
As he fights the monsters, he activates an attack that shoots spears from his belt and finishes off, Jakuabyssis, with his mighty kick, Drive Mariposa. (As seen in the Youtube video below, starts from 5:00)
Crababyssis flees into the ocean to escape, but Kaito chases after him with a water scooter and drives Crababyssis back on land. Crababyssis summons a few Myuganoids, and Kaito pulls out a sword, Mitsurugi, from his chest. He destroys Crababyssis with Drive Mariposa (sword version)

Ichiro reverts back into human form and meets up with his son. Koushin Narumi is standing behind them and smiles. Ichiro decides to return the belt (in orb form), but a light flashes and Koushin transforms into Kaito. Kaito (Koushin) says he knew Ichiro had it in him, and as long as Ichiro values live, Koushin will see him as a fellow ally of justice and let’s him keep the orb. Koushin takes off with the water scooter and Ichiro decides he’ll pass on the orb to his son, Daichi.