Sgt. Frog Episode 171: Tamama, Rebellion is a Regrettable Reason / Kururu, When is He a House-sitter?
Episode 171 of 358 of Sgt. Frog, aired July 28, 2007, 25 minutes. Available with English subtitles and dub where released.
Episode summary
Tamama is going through a natural rebellious stage in his life and to help him get through it, the rest of the Keroro platoon and the Hinata siblings must go through a specific set of steps... but every time someone screws up, they have to start over again! Will Tamama ever get past being a delinquent?! Later, while Kululu is left home alone, an automatic invasion machine is about to attack Earth. The unlikely trio of Fuyuki, Natsumi, and Kululu team up to stop it! Though you never know with Kululu... Source: crunchyroll