Sgt. Frog Episode 176: Chibi Kero, Farewell to Summer Vacation!
Episode 176 of 358 of Sgt. Frog, aired September 1, 2007, 25 minutes. Available with English subtitles and dub where released.
Episode summary
Distressed by his summer homework, which he left until the last minute again, Fuyuki goes complaining to Keroro, who reminisces about his childhood one summer in which he did the same thing. Source: crunchyroll