According to a forum member, the demo is now in the Japanese XBOX Live Marketplace available for download. It is also in English.
"wow the game is amazing. combat system is just fun and the game looks amazing. Im definitly jumping on the hype train.
You basically get a time gauge to perform as many real-time attacks as you can with each party member. Then the enemy gets there turn, you can actually defend and time button press's so that you take less or no damage.
Again the game looks AMAZING. Crazy how the 360 is getting these type of games. Im liking this much more then Blue Dragon."
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The quote above is from the original thread starter in post #5