the ps5 has it very hard on the japanese market.

I'm not sure it does, when you look at this graph its actually very consistent with PS4 sales when the release dates are aligned. Nintendos handhelds destroy the competition as they seem to in almost every market, but static home consoles are still very much dominated by Playstation.

Edit - I've just come across this Famitsu article, has hardware sales number for the week and PS5 outsold the Switch - 43,692/57,903 [Switch/PS5]