- Sergeant Keroro (Debut)
- Private Second Class Tamama (Silhouette)
- Corporal Giroro (Silhouette)
- Sergeant Major Kururu (Silhouette)
- Lance Corporal Dororo (Silhouette)
- Fuyuki Hinata (Debut)
- Natsumi Hinata (Debut)
The first episode shows the world in ruins, as aliens have appeared to attack the city. Two children (Fuyuki and Natsumi Hinata ) are shown running when Natsumi trips. She tells Fuyuki to run on without her, but soon they are attacked by a mysterious group, the main one seems to shoot a red beam from an item and evaporates both Natsumi and Fuyuki.
However, as it turns out Fuyuki was dreaming. Natsumi decides to try and wake him up, failing in the process. Natsumi than decides to lie to Fuyuki, saying that there is an alien in his room. Fuyuki instantly jumps up, and stares at a wall that Natsumi has pointed at. The wallpaper on the wall reveals an actual alien, and Natsumi and Fuyuki stare in shock.
Keroro shows many similarities to the first episode of Keroro Gunso, however there are some differences.
- In Keroro, Inner Tokyo gets attacked during the day, while the original is shown at night.
- Natsumi is shown carrying a watermelon in the original.
- Fuyuki and Natsumi in the original were attacked in the city and they were only attacked by Keroro, however in Keroro they are attacked near their own home and while only Keroro is seen attacking, the rest of the platoon appear beside him.
- Natsumi is the only one attacked in the original.
- Natsumi's wake up strategy is different in the original and she is shown in her school uniform.
- The original showed Natsumi's plan working, and she pokes fun at Fuyuki before Keroro is shown. In Keroro, possible due to the time limit, Keroro is immediately shown.
- The episode is a tribute to what happened in the first episode of season one.
- During the scene where Natsumi and Fuyuki are talking a yellow star can be seen falling.