I think rakuten should display the bitcoin sign next to visa and mastercard, i had to register an account,enter my address/name just to check if they offer bitcoin, there are a lot of bitcoiners that won't necessarily be aware of this news.
Also they should add a note when buyer is asked to pay a certain BTC amount explaining what would happen if buyer does not pay the correct amount (i.e order cancel and refunded ) , there always gonna be people trying to pay a little less than the stated amount even if its just satoshis, human greed... this is an advice for every company actually cause the more btc is adopted the more this hiccup will happen.
I was also wondering why some company only allow btc payment from certain countries? rakuten for example is japanese co so why only in usa? doesn't make sense to me , i have nothing against americans btw