Resident tax on capital gains?

Hi all, sorry for the noob question..

I have been living in Japan for a little bit over two years now and work here.

Last year I sold some crypto, which I filed in my taxes as 雑所得 and wired ~20% of the gains to the city's tax office.

Now, I just received a 請求書 from the city's office for 10% of last year's income (including my capital gains) as 市民税・県民税.

Even though I already paid a 20% capital gains tax, and get resident tax taken from every paycheck (plus everything else), I have to pay 10% extra, is this right?

So this means the actual capital gains tax rate is 30%?

Thank you!