sakiSaki (咲-Saki) is an ongoing Japanese manga series written and illustrated by Ritz Kobayashi. The story revolves around a first-year high school girl named Saki Miyanaga who is brought into the competitive world of mahjong by another first-year, Nodoka Haramura. The manga has been serialized in Square Enix’s Young Gangan since June 2006 and has been collected into six bound volumes in Japan. A 25-episode anime adaptation by Gonzo aired between April and September 2009 on TV Tokyo.
Links:

Saki anime at TV Tokyo (Japanese)