Apologies for the wall of text, but I hope it helps clear things up.
If your info is set up correctly, you'll have a one-click button on Kindle purchases. If not, there'll be an "unavailable at this time" message on it. You need to register a real Japanese address to one-click, and provide a valid payment method for one-click, too. Payment from non-Japan is okay.
Get an address from Tenso.com. Follow the instructions on their site.
I don't know why some people can
only purchase through a VPN. I've been able to purchase both with and without one without problems. Publishers retain the right to sell to "JP IP Only" for some books, in which case a VPN is really handy. (Select a Tokyo server and you're good to go.)
The quoted stuff below explains it in detail. Skip it if you want.
If you want a Kindle device, buy one in your home country. Don't buy one from Amazon.co.jp unless you are living in Japan with a real Japanese residential address. (Or buy one off of eBay.)
In terms of awesomeness for studying Japanese: First gen Paperwhite (EY21) > Second gen Paperwhite, iPad App > Fire App > Android App. The Paperwhites aren't that great for manga.
I find it's easier for me to keep my two Kindle accounts sorted out by using two different email addresses, one for the US, one for Japan. And I have two Kindles, too, one for each. Pain in the butt? You bet. But not a dealbreaker for me.
Sometimes the store will barf on a credit card purchase, just because. Check with your card company to make sure they didn't flag it for possible fraud, then resubmit it using the account pages, and go have a coffee while it sorts itself out. It's happened to me a couple of times, and it's not a big deal.
This following stuff might be helpful for some people. (Might not.)
According to this link:
https://www.amazon.co.jp/gp/help/custome...=201270030
Quote:旅行中のコンテンツ購入
海外旅行中でも、Kindle端末からコンテンツを購入できます。購入にはWi-Fi接続が必要です。
旅行先でWi-Fiネットワークを使用できない場合は、コンピュータ上でAmazon.co.jpからコンテンツを購入し、USB経由でKindle Fireに転送すると、端末からそのコンテンツにアクセスできます。
なお、コンテンツの購入には、居住国として日本国内の住所が登録されている必要があります。
Rough translation:
"Buying content in the middle of a trip:
"
Even if you're in the middle of an overseas trip, you can buy content for your Kindle. A Wi-Fi connection is required.
"If there is no Wi-Fi at your destination..." (stuff about connecting to website and downloading to Kindle Fire omitted)
"Also, regarding the purchase of content, for your country of residence,
a Japanese address must be registered."
and this bit:
Quote:海外での購入制限について
Kindle端末は、日本国内にお住いの方のみへの販売となります。
また、出版者または権利者により地域制限が設定されている場合があるため、一部のKindle本は日本国内のお客様のみに提供しております。この場合、お客様が日本国外にいらっしゃる場合は、ご購入いただけません。
Rough translation:
"About overseas purchasing restrictions:
"Kindle
devices will only be sold to residents of Japan." (Don't try to buy one! Buy it locally!)
"Furthermore, in the case that local/regional publishers or rights holders set access restrictions,
certain Kindle books will only be sold/provided to customers in Japan. In that case, overseas residents will not be able to purchase these books."
Anyway, there ya go.
EDIT: tried to make it more useful/comprehensible, made wall of text bigger.
Edited: 2014-06-07, 12:33 pm