What would happen if Rokudou loses his Haori of the Underworld?
During Episode 18 &amp; 19,


   The Shirushigami Kain seizes Rinne's Life Flame and Haori as payment on a debt.
 By declaring that the Haori will sell for a good amount implies its financial value.
 
 As shown in other episodes, he is unable to fly without his Haori, as he is only a half-shinigami. Whereas, Ageha can fly without needing one, as she is a full shinigami.
 This means that he would be unable to travel through the reido (without aid), which would prevent him from carrying out his shinigami duties, tracking his father, etc.