Man I wish they localized the PSP version of it, I love the phantom brave on the psp, and even better on the vita (the stronger console got rid of the island lag).
It's a strategy RPG where the strongest man in the universe is tricked into destroying his empire and becomes a Tome. So yeah, you basically play as a book that summons your own units to fight, and said units can throw the book to move their base. It's closely related to Disgaea and is by some considered a spinoff along with Phantom Brave and Soul Nomad.
I personally hated Phantom Brave... It's really the only game made by NIS that I don't like. To go further into I got it for the PSP and then turned around and sold it back to the store I got it from. The only character worthwhile in it to me was Ash, and I didn't like the story enough to continue the game.
This music also comes in the DLC for DIsgaea 2, is good to hear it when you fight in the item world. Can ask for an extended version of "The Great Wilder" from Makai Kingdom? Has the best version of that track in the whole NIS games. Or Rock & Rocks from Soul Nomad. I trying to work in my own versions, but aren´t that good like yours