I know you’re thinking of some scantily clad young white “to catch a predator” decoy, but it’s not even like that.
Instead it’s a type of fish. A tiny, tiny, tiny baby fish which is typically sardine/anchovies. If you also saw the post or the Japanese movie “Our little sister”, you might remember them eating this throughout the movie. The dish in the picture ($7.50) uses one of my favorite ingredients, myoga (it’s like a shallot mated with ginger). The other part of the dish is of course shirasu-ae (whitebait mix).