This is a single music video from a children's program that nobody can find anymore. The song itself, simple, patient, achingly human, carries the whole weight. It's the kind of thing that stays with you not because it's trying to, but because it isn't trying at all. Lost media has a gravity all its own. What survives by accident often matters more than what survives by design.
A single-episode music video made for the song Imouto wa Onaka ga Itainda, credited to Yumiko Kokonoe. The animated piece was featured on NHK's Minna no Uta program. Today the video is regarded as lost media, so no copies of it are known to be available.