Fail in payment in Japanse paypal site

Hello This is Suzuki from Japan.

I fail to pay with paypal express checkout.

I installed and upgraded Membership premium from Lite version, then tried to payment
in Japanese paypal and by Japanese yen.

However once I click the button, then visit to Paypal.com/jp/ , I couldn't see a correct merchant page.

Just they said "Data haven't matched the default encoding or imput letter set."

Then stopped.

All I have to set up in membership plugin about payment of Paypal is just type my paypal account and chose Japanese site??? or should I have to do another?

(I rewrote gateway.paypalexpress.php, just put Japanese paypal site in like 'JA' => __('Japan', 'membership'),)