Advice for credit card and sim card

I'm a japanese citizen moving permanently to Japan soon. I wanted to ask for suggestions on:

1. What credit cards can I get ASAP

2. Which physical sim cards (with phone number) should I look for. Not looking for heavy data usage, but good data coverage is important (esp. in inaka)

I know this question has been asked a lot but since a lot of the problems seems to stem from being a foreigner, I was wondering if the answers will change if it's for a japanese citizen.