There is a monster named "Black Devil" in the rivers and lakes. It is ever-changing, and its original form is just a ball of black energy. The Mu family has been exterminating monsters for generations. After hearing about the evil deeds of the Black Devil, they decided to kill it. The head of the Mu Mansion personally confronted the Black Devil. Unexpectedly, the Black Devil was very powerful. In the end, the Shogunate Patriarch and the Black Devil died together. This was supposed to be the end, but unexpectedly the body of the black demon decomposed into more black demons, smaller in size and less powerful than before, but superior in number. In order to prevent these black demons from continuing to be the only daughter of the head of the family sent by the Evil Mu Mansion, they went to the place where the black demons were to eliminate them.
Intention: a sudden whim