Lost Odyssey, Mistwalker’s Xbox 360-exclusive RPG, will be receiving yet another round of downloadable content in Japan this Thursday.

The new content will cost 400 Microsoft Points (about $5 or ¥592) and will introduce a new underwater dungeon on the game’s fourth disc. Playing through the dungeon will unlock a powerful new item that reduces the magic cost of spells.

No word on when this new Lost Odyssey content will arrive on the Xbox Live Marketplace in the West.

While I’m all for expanding a game’s content and extending its lifespan after release, even I have to admit that five bucks for a single dungeon only accessible from a very specific point in the game hardly seems worth it. At 89 MB, at least we can download knowing we’re not just paying to unlock content already on the disk.

Xbox News: Lost Odyssey DLC out this week [CVG]