Sgt. Frog Episode 153: Kerokero Military Operation, Number 100
Episode 153 of 358 of Sgt. Frog, aired March 23, 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