You could get AppleCare but Apple is unlikely to perform any service on an i-device bought in another country regardless of warranty type. Service often involves complete replacement of a unit with an identical refurbished model. Japanese iPads won't be available in the USA so read the "may restrict" below as basically saying "won't"
http://www.apple.com/legal/warranty/products/iphone-english.html
Note this statement from the iPhone and iPad warranty:
"IMPORTANT RESTRICTION FOR iPHONE AND iPAD SERVICE.
Apple may restrict warranty service for iPhone and iPad to the country where Apple or its Authorized Distributors originally sold the device."*
The above is from the USA version of this iPhone, iPad and iPod warranty document, but this particular section limiting international coverage is much the same for the warranty for all countries. If you wish to check the warranty for where you bought your device, click on this link to take you to the page about Apple warranties, then select your device and country --> Legal - Hardware Warranties - Apple
* The EEA (European Economic Area) is considered one country for warranty purposes: Dated 04 01 21 "Apple may restrict service for Apple Watch, iPad and iPhone to the EEA and Switzerland." - http://www.apple.com/uk/legal/statutory-warranty/