- Sergeant Keroro (major role)
- Private Second Class Tamama (Minor Role)
- Corporal Giroro
- Sergeant Major Kururu
- Shin Keroro (major role)
- Natsumi Hinata
- Angol Mois
- Dolphin (Debut)
- Dolphin's Parents (Debut)
The episode begins with Keroro and Tamama swimming away from a shark. Inside of Keroro's Secret Base, Angol Mois, Kururu and Giroro are shown watching as Giroro comments on how it was Keroro's plan, to which Keroro tells him to send them back. Mois questions Kururu on how to save them as he tells her to pull the red lever, when she does however it breaks having a huge wave of water to crash down inside the base. Keroro and Tamama make it along with some fish and broken levers as Keroro thanks them. Suddenly Mois points out something as a tail is seen flipping up and down, capturing Keroro's attention.
At the Hinata's House, Natsumi is shown complaining about the weather when the backyard door slides open, revealing Shin Keroro completely dehydrated and tired looking. Natsumi asks what's wrong as Shin complains about the overdose of water on the planet as Natsumi wonders why, seeing as how every time Keroro is in the rain he is happy. Natsumi then remembers something to help Shin as she brings a plate of Starfruit, Shin questions what it is and Natsumi tells him as she gives him a piece. Shin instantly feels better as he flies forward and head bumps Natsumi. He thanks her as he tells her that he was glad she was so understanding about the thing. Natsumi is shocked until she brings Shin down to the base and threatens Keroro about what the secret thing is. He then reveals the dolphin as Natsumi and Shin watch in wonder. Keroro explains how they found it as the Dolphin says hello to Shin and head bumps him. Keroro seems pleased until Natsumi and Kururu remind him of the costs of having a dolphin, Keroro quickly decides that he needs to return the Dolphin home, as Shin happily asks to join him. The duo quickly head over the oceans as Shin compliments them, Keroro agreeing with him. While they fly Shin notices two other dolphins near an island as he quickly recognizes them as the Dolphin's parents. He says goodbye as the head bump one last time as Shin asks if Dolphin will be all right, Keroro promising he will. Later on we see Keroro and Tamama running away from a lion and a rhino with Shin riding on the Rhino, Mois and Giroro are watching as Shin yells in joy.
Note: The File is mainly focused on the chapter 190, so the differences noted will be about that chapter.
- In manga the dolphin is seen wearing a crown that Natsumi was wearing when she was a princess of Planet Maron in Movie 2. Also, Meru, Maru and the other Maronians made cameo appearances, while in Keroro all references to Planet Maron along with Meru, Maru and the other Maronians are removed, and the crown was replaced with Kururu's symbol on its forehead.
- In Keroro, Shin didn't take the symbol off of the dolphin's forehead.
- In the manga, Fuyuki makes an appearance in this chapter.
- Towards the end when Tamama and Keroro run from the lion and the rhino, Shin is absent in the manga.
- Neko makes a cameo in the original manga.
- This episode marks the first time where Fuyuki is absent in the Keroro Flash Series, not making any cameos or a minor role.
- This episode is based on the chapter 190 with combined scenes from the chapter 187 where Natsumi is feeding Shin Keroro with star fruits.
- This episode shows that Shin Keroro is the only Keronian who hates rain and water in general.
- When Keroro is swimming and running away in fear his stomach is colored the same as his skin.
- When Natsumi tells Keroro to take Dolphin back to its home, the spiral on Kururu's forehead is switched backwards.