Best Anime and J-Pop Instrumentals

I’m searching for the best of instrumental from vocal songs. Say like opening and endings of anime songs but their instrumentals. Doesn’t necessarily have to be songs from anime either. It could be J-Pop songs that you’ve just happened to here. Please provide name of song, name of anime (if it’s from an anime), artist, and a possible link so we can hear, may it be a youtube link or a direct link to megaupload.

One of my favorite instrumentals is Every Heart from Inuyasha by BOA.
YouTube – BoA – Every Heart (Instrumental Version) Cover (http://www.youtube.com/watch?v=lHYEil2_fnE)

I’m looking for instrumentals that can match or top this song because it’s freaking incredible. A direct link for download will be provided later.

So tell me what’s your favorite instrumentals…..

This isn’t J-pop, but it will rock your socks anyway

Nebula (http://www.youtube.com/watch?v=oO4tbqYkgD0) – Tripshots

Edit: The Rozen Maiden Traumend Opening, Seishoujo Ryouiki (http://www.youtube.com/watch?v=Tsp1JJbBwvo) by Ali Project, is still my favorite anime opening, even though the anime itself is not a favorite.