^
I use my American credit cards when possible, but not every store will accept them. Here is the basic rundown of the most common places I shop at:
Yahoo does not accept any of my four American-issued cards despite all of them being Visa and working at 9/10 stores out in town. Yahoo makes up for around half of the orders.
Surugaya online orders are hit and miss. I think it all depends on where the item is being shipped from. Sometimes I can use American cards, sometimes I can't. At their physical stores, I can always use them.
TOPS is bank transfer or COD only when ordering domestically. Therefore, I need the cash in my bank account ASAP.
BEEP, Mak, and KVC Lab will accept my American cards.
Game Kanaya is super old school. COD or bank transfer only. Phone inquiries only if you have questions.
^ (Regarding this store, a window shopper made me look really bad to the owner of this store and I had to embarrass myself and apologize profusely over the phone. Long story short: imagine if you got fitted for a custom suit and then said "Nah it's cool, I got one from Sears" after the shop finished making it for you. Because of the experience, I will only call for repeat customers from now on.)
Most of the console shops in Akiba with the exception of 'Friends' (cash only) will take my American cards.
Edit: Should have specified in the previous post, but the 1.5% only needs to be added for stores that can not accept my American card.