Shadow Swingstress

The Shadow Swingstress is a character in Mario Tennis: Power Tour who follows the player's progress in the story mode of the game. She's an unranked junior player who's thrilled to have another unranked junior in her class, and initially assumes she can catch up with Clay and Ace, then sees their talent level and begins to ask them for advice. Her real name is unknown but resembles the appearance of Nina. The title "Shadow Swingstress" comes from a nickname she got from other junior players. Her doubles partner is another unnamed shadow swinger only known as the "Shadow Swing King".

Other people in the junior class have made comments about their level of play. Sylvia and Sasha comment when playing against them, that they're easy opponents. She seems focused, but without direction. It's implied that Clay and Ace once they hit varsity serve as surrogate coaches and give her and her partner motivation to try to become better players.