Was just reminded of a helpful tip that my Uncle passed down. Restaurant tested and approved!
Kamaboko freezes really well. To defrost, drop it into a pot of boiling water (fish side down and still shrink wrapped) then lower the heat to simmer. Cook for ~30 min or so until it’s heated all the way through. Remove and allow to cool before opening. Texture and taste is the same as if store bought.
I’m guessing that boiling tightens everything up again and helps to avoid the spongy texture you get if left to defrost in the fridge. Hope this helps!