Akagi (アカギ) is a Japanese manga, written by Nobuyuki Fukumoto. Needless to say Akagi is heavily focused on playing mahjong. Akagi was first published in 1992. It's featured in the weekly magazine Modern Mahjong, and is a sequel to the Fukumoto's previous work Ten. In 2005, 26 TV episodes of Akagi were produced. The 26 episodes can currently be enjoyed on youtube
Links:

Akagi on Nippon Television Network (Japanese)

Akagi episodes can be found on you tube with english subtitles.

Saki (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)