When an alien bomb powerful enough to destroy the entire planet sticks to the buttocks of Shin-chan's pet dog Shiro, a race to save the world begins.

A vacuum repairman moonlights as a street musician and hopes for his big break. One day a Czech immigrant, who earns a living selling flowers, approaches him with the news that she is also an aspiring singer-songwriter. The pair decide to collaborate, and the songs that they compose reflect the story of their blossoming love.