Interest rates are much lower here than in the US, and airlines haven't really caught on to the idea of flogging points to banks for cash. As a result, credit cards tend to have very low signup bonuses and high annual fees (that are rarely waived). Category bonuses for spending tend to be poor as well. The best I've seen is Amex's Sky Traveler Premium Card that gives 5x points for airline tickets. However, the annual fee is about 30,000 JPY and you can only generate a maximum of 80,000 points with the bonus, which kills it for me.

Manufactured spend is also nearly non-existent. I've seen Vanilla cards in convenience stores but there's no way to easily liquidate them back to cash like in the US. I've heard one way of doing MS is to buy Amazon gift cards, then sell them online at a gift card marketplace, but the overhead doesn't make it worthwhile.

Remember, this is the country where mileage runners think 7-8 yen per mile on NH or JL in Y is a good deal! The economics of CC spend and mileage accrual are simply different than the US.