Sgt. Frog Episode 155: Keroro Platoon, Cut a Good Tune! / Keroro Platoon, Large Resonance!
Episode 155 of 358 of Sgt. Frog, aired April 7, 2007, 25 minutes. Available with English subtitles and dub where released.
Episode summary
The Keroro Platoon comes up with a new, catchy tune to win the hearts and minds of Pekoponians, starting with the kids at Kissho Academy. Later, when the platoon enters an HQ-sponsored resonance contest, they find that their resonance has unpredictable physical effects on a variety of things around them. Source: crunchyroll