Recently I've learned the new term Credit history. Artur and Yann adviced me to create an AMEX card in Japan and switch to US one, since they keep the credit history intercontinentally.
Well, what is Credit History anyway? It's pretty new to me since there's no such a thing in Japan: You don't need to re-pay after using credit cards. Just create a credit card and associate with your bank account, then the price you need to pay will be automatically subtracted from the bank account monthly. I guess creating a debit banking card would be the easiest choice in US.
You need a credit history to create a credit card, and you need a credit catd to build a credit history. Nice chicken-egg here.
I need to learn more about these stuff.