Here you can download the official rulebooks:
This is the first rulebook. It comes with the Light and Dark faction starters, and is available from cipher-studios.com. It covers all of the basics, and is the starting point of choice to learn the game, but lacks depth.
Check this website for extended rulings and clarifications, or ask in the Official Anima Forums, where a really friendly and helpful community, and the game makers themselves, will be happy to assist you! (Seriously, it's a great forum).
This is the first of two supplements to the first rulebook, explaining new rules not present when the game was first published. This addendum covers Critical Hits, Throws, Ranged Attacks with Area Effects, Damage Resistance (aka Damage Accumulation), Stealth, Innate Abilities, Special Deployment and Victory Points
Scan from the back of the Saga I & II Rulebook.
Scan of the Black Sun rulebook that comes in the new Starter Box