May, known as Mayumi in the Japanese and Italian versions, is Charlie McCay's niece which appears in the second arc. She is currently ill.
May appears as a young girl with blue hair and purple eyes. She wears a yellow shirt.
World Duel Carnival
May was going into surgery for an unspecified condition and was nervous. Charlie McCay, her uncle, gives her "Number 7: Lucky Straight" as a token of good luck and tells her to do "kattobingu". The card comes later into Yuma's possession.