One separate issue: stripe_country seems to be set to US. I expected it to be Japan, but I guess this value is coming from Stripe and is related to the sandbox credit card information being used. In includes/modules/payment/stripepay.php we have:
'stripe_country' => zen_db_prepare_input($charge->source->country),
I hope I am right in assuming this means the value I see is coming from Stripe's sandbox client.