C: The Money of Soul and Possibility Control

Synopsis

Kimimaro finds himself up against one of his professors, Mr. Ebara, and defeats him, making him bankrupt. The next day, Ebara brings Kimimaro over for a talk, revealing that he entered Deals to support his family, and his punishment for bankruptcy made it so his children never existed in the first place. He also mentions the Starling Guild which Mikuni is a part of, supposedly trying to prevent the Financial District's effects on the real world. Mikuni brings Kimimaro to observe one of his duels against another high level Entre, purposely holding back his strength to win by a 1% margin so that he doesn't affect the real world. After witnessing the duel, Kimimaro becomes determined not to lose so he doesn't have to make anyone else suffer.

(Source: Wikipedia)