Now a days, the most easiest way to do online shopping is to shop through PayPal.
It is also the easiest and the
cheapest way to send money through
international transfer.
In Japan though, not many small companies wants to do international shipping. To them it's too much hassle and in Japan, not many small companies wants to tolerate with return policy unless the product is actually broken. In Japan, it is very uncommon to return the product unless it is broken. Whenever international customers tries to buy product from a small Japanese company, one problem they have is that it's very inconvenient to do international shipping. The other problem they have is when buyers do refund after the product is already sent, then the Japanese sellers gets frustrated because of the time and effort they have to put up with all the trouble. So many small Japanese companies gave up on PayPal. It sounded good for a while, but eventually it causes problems for unreliable buyers, especially when they don't read English all that well and can't tell if the address is verified.
The most common way for small Japanese internet shopping companies to transfer is called "Ginko-Furikomi", which means Bank transfers. On every Japanese ATM's, they have a selection where you can do a domestic money transfer. The fee is 210 yen if the transfer is within the same bank and 420 yen if it's from different banks. It's fast and easy for Japanese, but not easy for foreigners, because all the menu's are in Japanese. This is how most Japanese pays their bills.
Another common practice for money transfer is going through post office or convenience stores. If you have a bill to pay, most consumers go to convenience store or post office and pay. After you pay, they give you a stamp and a receipt that you are paid in full. How do electric companies or other companies know you are paid in full? Every receipt has bar a code and it's scanned.
Credit Card is also very new for Japanese consumers. Believe it or not, most Japanese still don't have credit cards.