Along with Mr. 7, Miss Father's Day is part of the "sniping" pair who apparently are deployed for jobs by the Baroque Works where sniping is necessary.
Miss Father's Day first shows up in the main story briefly during the climax of the Alabasta arc manning the giant cannon that Baroque Works had placed in the Alabasta capital, Alubarna. Princess Vivi figures out the location of this cannon and, during the final moments of the battle of Alubarna, she (with the Straw Hat Pirates' help) attacks it. Miss Father's Day and Mr. 7 attempt to stop her, but Vivi skillfully evades their gunfire and defeats them by using her peacock slashers. Miss Father's Day was also responsible for sniping down an airborne Pell while his attention was occupied by looking for the bomb and at Vivi and the Straw Hat Pirates. It is unknown what happened to her after the war.
She is voiced by Cynthia Cranz, who is well know for voicing Chi-Chi in Dragon Ball Z.