Just messaged a contact in Nagoya... see what he says. I've personally never been to Nagoya, but it's not too far from Osaka - we had two people from Nagoya bullet train it to Osaka for the fan meet there earlier this year. If you go to Osaka and you can speak Japanese, you can haggle with staff at Hero Gangu (which is a rarity in Japan -- you can't haggle at other places).

Otherwise you can go to any regular toy departments or toy stores (e.g. TRU) etc. to check for current stuff like Masterpieces.