There's a total of 31 volumes of Slam Dunk manga. This great manga has recently been licensed by an American company, hopefully, all SD fans will be able to purchase English edition of Slam Dunk manga.
As often discussed by fans, the manga did continue on to the national games. We get to see further improvement for both Sakuragi, Rukawa, as well as for all other major characters.
If you are eager to find out how Shohoku did in the national competitions, check out the stats section, we have game scores available. Although I'm sure you don't want to miss the excitement of reading how the actual games went. ;D
We will definitely post information on where to purchase the mangas for you here as soon as we hear news on it, stay tuned for SD to become a popular anime in the west world, among English speaking fans!
Manga Summaries - Volume 25 starts after the anime ends
* More volume summaries coming shortly