Japan’s instant game library includes two TurboGrafx-16 titles this month. If you have PlayStation Plus tied to a Japanese PSN account you’ll get New Adventure Island and Gradius. That’s cool, but probably not a reason to sign up for the service in Japan. Right now, the selection of games is rather lacking compared to North America and Europe.
The other PlayStation Plus titles for Japan are:
Sonic the Hedgehog (Genesis version)
Crazy Taxi Double Punch
God of War HD & God of War II HD
Everynya’s Putter Golf
Ratchet & Clank: Quest for Booty