lets see at which point yen turns into SGD
1. you charge your ishibashi purchase to your credit card
2. ishibashi charges the credit card company in YEN
3. at this point, i am not sure, but it is either of the 2:
a. credit card company converts yen into SGD based on their own exchange rate
b. bank that issues you the credit card converts yen into SGD based on their rate
4. it gets onto your credit card statement in SGD. you get your credit card statement and whine. if you're using debit card you will suddenly one day discover that alot of money is gone. and then same thing, you whine
so the exchange rate depends on the credit card company or the bank. i think it's the bank. someone correct me if i'm wrong 8)