Sgt. Frog Episode 178: Momoka, Ghost: The Hinata Family`s Phantom
Episode 178 of 358 of Sgt. Frog, aired September 15, 2007, 25 minutes. Available with English subtitles and dub where released.
Episode summary
Still too shy to say anything to Fuyuki about wanting to spend time with him, Momoka begs the Keroro Platoon to turn her into a ghost so that she can follow him around to her heart`s content. Kululu`s machine may work, but... is there actually any way to turn her back again? Source: crunchyroll