Episode 323
When Keroro's left home, he appreciates it at first, but then finds that having the run of the Hinata house isn't all it's cracked up to be. Later, when Natsumi borrows a Kero Ball to use as a video camera for a contest, she soon finds herself in the middle of a dangerous combat cameraman training simulation... inside the ball itself. Source: crunchyroll
Aired 17/07/2010EP 323 - Episode 323
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)