=====The Album===== A rare album with no crappy filler songs. It features the Black Cat opening theme "Daia no Hana"- for which most people are probably buying it- but as I've never seen that anime I just bought it because I like the music on the single. My favorite track is "Hikari N.Y. Version"- it's one of those sad-but-beautiful songs that sticks in your head even if you haven't heard it for years (the fact that it's also a rare anime song in English may contribute to this...) The CD also includes the Japanese version of the same song.
While "Daia no Hana" is the typical upbeat, pop/rockish thing you can expect from anime opening themes (even the most depressing series have upbeat opening themes) the other two tracks- variants of the same song- really far surpass it. This is a notable exception to the trend of most anime theme singles having the themesong, its karaoke version and one otherwise-unsellable crap song by the same group/singer. And the opening themesong itself is actually GOOD, even to people who- like me- haven't seen the anime. (Most themes are only good for nostalgia- would anyone *really* like Moonlight Densetsu if they hadn't seen Sailor Moon? methinks not.)
The album is worth a hardcopy purchase, to rip and savor in high-quality AACs, rather than just buying the mp3 version (which only works for Japan residents anyway...) (although listening to the sample of it on that page *does* work: http://www.amazon.co.jp/gp/product/B0046E5DEY )
=====The CD Version===== I looked on Ebay, CD Japan and YesAsia for this- as well as trying to buy from the Japanese Amazon mp3 site- and the only place an American can reliably get this album is in hardcopy from Amazon.com. (Although I did purchase a copy from YesAsia, who- after taking my money- helpfully informed me that they didn't have the item after all, but I *could* have store credit with them instead of a refund. Ummmm...) I'll save other searchers the trouble: as of 2013, the Amazon.com listing is literally the only US-accessible place I could find this album legally for sale. That may be subject to change (hopefully!) but for now, that's the case.
=====The MP3 Version===== The (LEGAL!) MP3 version of this album is available on the Amazon.co.jp website's mp3 downloads section for MUCH cheaper -BUT-  you must be a Japan resident to buy it -and-  the sound quality is much lower than buying the hard CDs.
Also, the hard version comes with a song booklet which includes lyrics, and (as I found out the hard way when wanting to tag the files) lyrics for some of these songs are pretty hard to find online.
Anyway, the link to the MP3 purchase page is here, -IF- you can buy from it: http://www.amazon.co.jp/gp/product/B0046E5DEY
You can also listen to short sample clips of the songs on that page, which you probably *should* do if you're about to shell out $20-30 USD for a small CD single.
=====Tracklist===== (Since Amazon doesn't tend to list tracklists for rare CDs...) 1. HIKARI ("light") 2. ダイアの花 (daia no hana, "diamond flower" or "blossom of diamond") 3. HIKARI -N.Y. version- (English-language version of track #1)
[The append "N.Y." for the English version of Hikari /might/ be a homage to New York City after its tragedy, which was kind of recent when the CD came out... not sure.]
=====LYRICS===== 1. HIKARI [...] (Finding an English translation of the Japanese version, rather than just the English *version* of the song, has so far proven impossible. If you have a link to a translation, please reply with it and I'll add it to my review.) 2. Daia no Hana: [...] 3. HIKARI -N.Y. version- [...]