> I bet that most, if not all, decent restaurants in Japan ultra-freeze wild fishes on the other hand, even if they may not admit it.

They (can, in some restaurants or if you ask) serve the head next to the sashimi and it is still twitching so you know it is fresh. So no, they don't.

So the parasites don't exist in Japan or they don't affect people who eat them?

> The Health, Labor and Welfare Ministry has issued an official warning on the rapidly growing number of Anisakis infections linked to eating raw or undercooked fish. [...] The ministry urges consumers to keep the fish frozen below minus 20 degrees for at least a day, or heat it for at least for a minute in temperatures exceeding 60 degrees, which should kill the larvae.

https://www.japantimes.co.jp/news/2017/05/12/national/scienc...

My understanding is that for many fish species, the fish are caught well offshore on multi-day fishing trips. They are put on ice immediately, otherwise they return to the docks with spoiled fish. Think "The Perfect Storm".