Yuki is the younger sister of Ai's dead mother, in other words her aunt. She looks so much like her sister that when Ai first meets her she mistakes her for her mother. She, like the rest of her family, carries the "witch sequence" in her DNA and is most likely a Hot Witch, though this is never clearly stated it's most likely due to her ability to use Cleansing Fire to chase away the Shadow of Death. Her powers as a witch are very powerful. She's loud, ditzy and, well, just crazy most of the time but she has her serious side as well. She seems to know a lot about witches and the craft.