When I gocto a shop in Japan, whenever I pay for something with a credit card, I am always asked if I want to charge my purchase more than one. My Japanese isn't very good, so I may be misunderstanding what is being asked, but what is the reason for this?
Qualifier: I live in Japan and have several Japanese credit cards.
The "ee-kai?" (one time) question you get asked at the register is how many payments you want to make. One, two, five and so on. There is also "bonus-kai" which will match your payment due date to the semi-annual bonuses paid by many large Japanese companies.
Credit cards in Japan are more like charge cards as the balance is due in full each month. Thus you have to decide the number of payments at the time of purchase. You can't change it later.
Also oddly, a 2-time payment or bonus-time payment choice usually doesn't charge interest. So you get an up-to-6 months interest-free loan out of it.
Japanese credit cards usually allow you to pay for purchases in two monthly installments, at no extra cost. If you want to do this, you must mention it at the time of purchase, which is why many shop clerks will ask (lest you forget). I do not know what happens if you try to do this while your (presumably foreign) card does not allow it.