AkagiAkagi.

Akagi: Yami ni Oritatta Tensai (アカギ 〜闇に降り立った天才〜; lit. 'Akagi: The Genius Who Descended into Darkness') is a Japanese manga series written and illustrated by Nobuyuki Fukumoto. First published in 1991 in Takeshobo's weekly magazine Kindai Mahjong, it is a spin-off prequel to the author's previous work Ten. It revolves around Shigeru Akagi, a boy who defeats yakuza members well versed in mahjong at 13.