Willenskraft

Shinigami never bothered much with the Human World, so they were oblivious to a secretive, underground world called the mafia. Even then, both Shinigami and Quincy didn't know of dying will flames, a power Vongola and its allies liked to keep secret. Except Namimori and Karakura were neighbors, and Souken knew who to contact when Uryuu accidentally set a tree on fire. Oneshot