Cheers
Littlemike
These places that are charging $100 are a little more than doubling the actual price. However, they're using their local address in Japan as the billing contact to fulfill the local residency requirements on your behalf. Personally I haven't seen a registrar with an English interface offering lower than $100 for a .jp name.
I have no experience with .kr names, but they're probably quite strict on the local residency requirements otherwise I think you'd see a lot more of them. China just opened up the second level .cn names less than 24 hours ago and there are no restrictions on residency at all for them.