Black/Matrix 00 is the last and chronologically the first game in the series so you’re not missing out on much if you start here. The game was originally called Black/Matrix 0 on the Game Boy Advance, which was ported to the PS1 with added voice acting. That’s the version on Japan’s PlayStation Store now.
Black/Matrix 00 costs 600 yen ($7) just like this week’s other new downloadable games, Family Chess and Sentimental Graffiti. All three games are PlayStation 3 and PSP compatible.