DTK x witch reader

Y/n and her sister s/n are a rare powerful witches. They both share the power of yin and yang... but the two of them had to make money as the grand witch their mother is very old and cannot take care of them anymore... So the two witches both decided to work for Medusa.. y/n was hesitant about it but she knew, she needed the money. As planned, Medusa gave them a task.... she told her sister s/n to help her as y/n to spy on the grim reapers son. Little did y/n knew Medusa secretly injected venom inside of her but in order to keep it from worsening she have to take the grim reapers sons power as that is her whole task to awaken the Kishin. But will y/n for fill her task or face death.... in the long run....
......