Kimchi in Japan is not fermented?

So I heard the kimchi (Japanese call it kimuchi) for sale at the grocery stores are not fermented. Is there a way to make the already store bought kimchi bought in Japan fermented by just leaving it in the fridge a long time like past the expiration? if so for how long? or if not does the store bought kimchi in Japan need to need to sit in a jar (non-refrigerated) for some time?

Even in Korea, each family has their own "recipes" for their kimchi, so flavors would vary to some extent.

Having said that, the Japanese might have adapted the original recipe to suit the local preferences better, and some make it with less red pepper than in Korea, and some make it with far less lactic acid fermentation than in Korea. There are some brands of Japanese kimchi sold at supermarkets that specifically advertise that it is not fermented (so it's more like pickled vegetables with red peppers).

I guess you might want to try some Korean food stores in Japan if you want the more genuine flavors - letting them sit might just make it go bad...

No, letting the Japanese kimchi sit in fridge will not work, it will go bad.

The Korean kimchi is heavily salted, squeezed and drained before mixing in peppers, fish sauce etc for fermentation. Japanese kimchi is often made minus the initial processes.

For Korean kimchi, original packed version from Korea, try the couple Korean stalls along Ameoyoko.

or get them from chefs in restaurants at the Korean sector the other side of Okachimachi.

There are about 10 different brands of kimchi sold at our local supermarket and I recall some noting how many days it has been pickled. The longer the more fermented.

We also have several authentic Korean food stores in our neighborhood and when I once bought some kimchi from one of them the shopkeeper told me it hasn't been long enough implying I should leave it for a while.

As suggested, it might be best if you shop at a store where they sell their own homemade kimchi or at least a department basement store where the clerk can be more knowledgable.

I am not sure if you just want to experiment Japanese kimuchis turning into the Korean kimuchi or simply want to buy the authentic one.

In supermarkets, you may be able to some imported kimuchi which should be way better than most of those cheap fake kimuchi. I agree that we would even call them kind of kimuchi...they wouldn't change into the real one. It is not a matter of time.

Other choice is that you can find a kimuchi shop on the local streets run by like Korean family and selling good homemade ones.

I usually buy kimuchi at such small kimuchi shop nearby, where you find more variety of kimuchi not only made by hakusai, but moyashi, daikon, kyuri, etc... Moyashi (sprout) is my favorite.

Just so you know not all Korean kimchi is fermented so much. Sometimes harvest times, you make it and eat it right away. Fermentation is to allow a chance to eat it over a longer period of time since in olden days they did not have refrigerators ( they were placed in clay plots underground during winter).

I did see 'Korean brand' Kimchi in Japanese grocery stores, either in a jar or metal-type bag.