Mari Katsuragi (桂木 麻里, Katsuragi Mari) is Keima's biological mother and Elsie's adoptive mother. She runs a café named Café Grandpa.
Mari generally appears in the guise of an ordinary Japanese housewife who runs a café while her husband works overseas. She is a loving mother who constantly worries about the future of her son, Keima. She sometimes even has delusional nightmares about Keima marrying a cardboard cutout of a video game heroine and turning into a half-insane hobo. She is also very fond of her husband's "illegitimate daughter", Elsie (a little lie by Elsie for becoming a family member).
Before she was married, Mari was a frightening member of a motorcycle gang, where she was known as "The Snow Witch of the Mountain Pass". Whenever she is angry, she will revert to her previous violent personality. She is not a helpless woman despite adopting a very domestic personality, as shown when a storekeeper sexually harasses her which leads to her retaliating by brutally beating him up. Additionally she continues to maintain and ride motorcycles, which she views as a comforting habit that she uses to relax.
Even though she was "betrayed" by her husband (who has actually done nothing), it is shown that she still loves her husband deeply.