PrEP in Japan (Working Holiday)

Hello, it's a throw away account, but I would need your lights.

I'm looking into working holyday visa for Japan (from a EU country), and I have a question :

Do you think immigration would let me in with PrEP ?

I think PrEP in my country is mainly used by gay mens and sex workers, and I'm just gay (lol).

I don't know if they would be suspicious since it's medication that sex workers use, and WHV forbids sex work (wich is logic).

Is that a good idea to go with my PrEP at immigration with my prescription from my doctor in EU ?

Or should I get PrEP prescription in Japan with a japanese doctor/other ways ?

Thanks a lot in advance for your answers and advices !