Japan never signed the treaty so legally they are in no way bound by it. Something like the US never signed the "ICC" treaty so we are not bound by it.
And for some reason they never went after Norway or Greenland, who both still do whale hunts.
And Norway does not even eat their whales.
But hey it make people who have no idea of the difference between a narwhal, sperm whale, humpback whale or minke whale to run around spouting nonsense about the evil Japanese.
It’s not even a treaty, the IWC really started as a trade organization to make sure there was hunting stock. Then came the moratorium Japan never signed, then they started letting in a bunch of non-whaling nations.
I think they don’t go after Norway and Greenland because they’re not so brazen about it. Japan is all “yup, we’re hunting whales, wanna watch”. I think Japan is really making fun of the IWC but nobody seems to get the joke.