Kuni's family was captured by a demon. She ran into the woods where Jack met her, and when she ran back into the house, Jack followed her.
It is revealed through a series of spooky events within her house that she and her family are haunted by a demon that captures and imprisons souls, and can create areas over which it has physical control, thus allowing it to corner further prey.
Kuni frequently appeared guilty towards Jack as he attempted to escape the house, knowing that she had trapped him there. Once Jack defeats the monster and frees the souls of her family, she becomes happy and grateful.
It is unknown how the past Aku's destruction affected her and her family's existence in the future.
- Kuni was the only member of her family that wasn't captured by The Demonic Spirit, although it likely spared her simply to use her as bait to lure in more victims.