Episode 320
The frogs decide to try becoming super-hot humanoid men in order to tempt Natsumi to consent to their invading. It almost works. Later, Bariri shows up yet again in order to try to convince Pururu to marry him. Source: crunchyroll
Aired 26/06/2010EP 320 - Episode 320
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)