When the only country in the world that has had atomic bombs dropped on it puts a mushroom cloud in a movies, it tends to have more resonance than when, say, the Italians do it. When the Italians set off an atomic bomb, it heralds the arrival of post-apocalyptic, dune buggy-driving leather aficionados. When Japan does it, however, it is something heavier.
And just where is Sonny Chiba in all this, you may ask? Well, he does have his heroic moments, but the top-billed star seems mostly content to blend into the background and let all of the insanity just happen around him. Which is a very sensible attitude to take.