This has been featured around the Innernet recently, so why not here? Personally, my biggest skepticism is that I suspect it actually needs a mix of dark soy sauce and a much lighter sauce that floats on top?
I dunno though, maybe the ‘trenches’ are so deep that it works with simple soy sauce? Pretty dang clever, either way.
In the spirit of Starship Troopers, if you’d like to know more:
https://www.boredpanda.com/dishes-sauce-images-appear-3d-print-japanese-redestu/
I think we tend to use too much soy sauce anyway so this might be a sneaky way to make you use less?
If the itamae didn’t want me submerging my nigiri in soy sauce, he would have made it more buoyant.