Nobody makes optimistic sci-fi anymore. This 1969 special treats a kid's dream of building an underwater city like a real engineering problem, not a fantasy flourish. Tezuka plants you inside the stubborn hope of someone who refuses to accept that the future is something that happens to you instead of something you build. The special costs you nothing but fifty minutes, and it asks: what would you stake your whole life on if nobody told you it was impossible?

A young man spends his life chasing one dream: building an underwater city. The goal is treated as an ambition pursued in earnest, not as fantasy, and the story plays out as a realistic drama about his life rather than a flight of science fiction. The 1969 special was made for 20th Century Hour, an educational program on Nippon Television, and uses its sci-fi idea as the backdrop for a grounded human story.