Yukiyo is a 200 yr old (physically 23) demon who is an Entity Slayer. She has white hair tied in a long pony tail and a black and yellow katana that she can summon at will. She is bubbly,outgoing,and a DereDere. After Amichi saved her from a entity and cares about her despite being a demon she falls in love with him and makes a marriage contract with him. She deeply cares about Amichi and likes being around him. She gets jealous when her sister,Sia,flirts with him or if her ex,Renka is with him.