moving to japan for undergrad

I am an American currently living in America, but there's a possibility that next year ill move to Japan for undergrad. can american foreigners in japan tell me about how the banking system works there? What’s the best credit card for doing my undergrad in japan? will I need to get a bank and a card once im in japan? will i need to change banks from an American bank to a japanese one? what card has the best usd to yen conversion rates? what card makes transferring money easier? pls help me