The article isn't saying everything and the way it's written may mislead people.
Yeah, there is no reason to really panic, not only will those funds be accessible but also, quite funny, Kraken has a lot of experience in the field, this is the second time they are leaving Japan, after all, the first period they were active was 2014-2018, now it's 2020-2022, so probably in 2024 they will be offering their services again for a year, just in time for the halving!
Japan has some serious capital control laws, the whole MtGox fiasco has made them look for more regulations, higher security standards which are more costly for companies, with this bear market and probably lack of interest it's the obvious choice, you either adapt or you go out Celsius style!
Of curse, just because this might go smoothly it doesn't mean to trust Kraken with all your coins and leave them there for months!