Sgt. Frog Episode 181: Mushishi, Search for the Insects! / Momoka, Three-Legged Race!
Episode 181 of 358 of Sgt. Frog, aired October 6, 2007, 25 minutes. Available with English subtitles and dub where released.
Episode summary
A former Keronian assassin and insect fan shows up to tell the Keroro platoon that Pekoponian emotions can be controlled through the placement of bugs. Keroro insists they use Natsumi as the first test subject! Later, Momoka`s larger-than-life parents duel over which of them gets to participate in the parent-child three-legged race. Source: crunchyroll