Sgt. Frog Episode 154: Keroro, Farewell Sergeant Keroro
Episode 154 of 358 of Sgt. Frog, aired March 31, 2007, 25 minutes. Available with English subtitles and dub where released.
Episode summary
The Keroro Platoon is all set to come up with a doozy of a 100th invasion strategy! But then an alien invader, one who swallows up entire planets, approaches. Earth may be doomed. Source: crunchyroll