With the manga version, there are currently 3 seasons.
1st season is called Grappler Baki and has 43 books.
2nd season is called New Grappler Baki and has 32 books. (the ones you're downloading)
3nd seaons is called Hanma Baki and is currently on the 11th book, and ongoing.
If you have watched the anime, it already covered the 1st season of the manga (43 books), but since the manga is SO different to the anime, you'd miss out alot by skipping the 1st season.