Daisuke's mother and Daiki's daughter. She's very energetic and constantly embarrasses her son.
Being the only daughter of Daiki Niwa she could not be affected by Dark Mousy. But during her childhood she insisted on being told stories of the enigmatic thief spirit laying dormant in the male family members DNA. She is overjoyed when Daisuke first changes into Dark and proceeds to explain the condition to him with the help of his grandfather. She and Daiki arrange which artifacts Dark is to steal and then seals the curse within the item to stop it causing any more trouble.