I think the connection that has made here between this phenomenon in Japanese waters and what has been reported in Scandinavia is very intriguing. There certainly seem to be correlations between the Kraken and the Akkorokamui, and it interests me that indeed Hokkaido lies along similar polar routes and the habitats do resemble each other in many ways.

It also should be noted that as Dogu4 said, cold, oxygen rich waters are good places to find creatures such as this. The giant squid and the colossal squid are both found in very cold waters, dark waters.

It makes me wonder how they would come to the surface to be readily observed, but giant squid that are injured or distressed are known to do so, and it would be a good reason why something like this could remain unverified by science.

Great feedback here.

This looks like a cryptid that might actually be confirmed, maybe next year.

The comparison with Scandinavia is spot-on: both environments have a lot in common in both form and origin. One would expect to find the same species inhabiting both. While Scandinavia and Japan may seem to be a great distance apart, they really are not all that far removed from each other by a polar route. Easy for an underwater species.

We are culturally conditioned to think of the world as a Mercator Projection, which seriously distorts distances at high latitudes. Imagine the same area from a Polar Projection, and you can see the distance is a lot shorter.