Taiyaki was invented in 1909 as a cheaper spin-off of a round waffle cake — bakers shaped it like a sea bream, a fish tied to good fortune, so people who couldn't afford real tai fish could still eat one.
A waffle-like batter is poured into a heavy, fish-shaped iron mold, filled with a scoop of sweet red bean paste (or custard, chocolate, or sweet potato), then the mold is clamped shut and turned over a flame until the shell turns golden and crisp. Vendors hand it over wrapped in paper, still too hot to hold with bare fingers.