It´s yakuman not yakumon, the man part of it means full. It´s the same man as in mangan (you don´t say mongan do you?). The mini points you get are based on how you decide to use the tiles in the final hand. Sometimes there might be different ways to organize the final had which will give different ...

The Legend of Koizumi
http://en.wikipedia.org/wiki/The_Legend_of_Koizumi

Junichiro Koizumi (Japanese Primeminister 2000-2006) plays Mahjong against other world leaders including Gorge Bush Jr, Gorge Bush Sr, The Pope, Vladimir Putin and others.

1 Chapter translated:
http://xamayon.org/koizumi.php