I saw this animation movie when I was a kid, i think in the mid 90's, so it must be from that period or older. We had it on VHS, and it was probably direct to video. I'm pretty sure it's Asian, maybe Japanese. Anyway, these are the details I remember:
- This post-apocalyptic world is not a dark one, Mad Max/Fallout style. I remember a coastal town of simple living people. I remember a scene in which a past nuclear war is shown, with giant explosion engulfing the Earth.
- 2 protagonist, a boy and a girl. She has the ocarina, i think.
- They travel to some place, I don't know why and i don't know what they find, probably some explanation to what happened in the past.
- There are narwhals, but i can't place them in the story. I think I remember them being shown in the end, but i'm not sure. They are probably thought to be extinct.
- I remember a scene where some bullies tie toy balloons to a cat's tail. I think the protagonists scare them away and help the cat.
- There must be an adult, who searches for the protagonists and joins them at the end. He's probably a parent, or a similar figure, and i think he's a doctor or veterinarian.