Episode 309
When Keroro hits on a new way to slack off, Giroro gets to take command of the invasion plans for a day. He orders an expensive, powerful weapon but isn't thrilled when it goes haywire and tries to vaporize Natsumi. Later, Giroro takes the lead in another strategy, sending phone texts to Natsumi and then leaving her in anxious suspense by suddenly cutting her off. Except it doesn't quite play out that way... Source: crunchyroll
Aired 10/04/2010EP 309 - Episode 309
Sgt. Frog
Keroro is a frog-like alien sent from his home planet on a mission to conquer Earth. But when his cover is blown, his battalion abandons him and he ends up in the home of the Hinata family. There, he's forced to do household chores and sleep in a dark basement that was once supposedly a prison cell haunted by the ghost of an innocent girl. He even spends his free time assembling Gundam model kits. During his stay, Keroro meets up with subordinates who were also stranded during their failed invasion.
(Source: Anime News Network)