Sister Phantom (ファントム・シスター, Fantomu Shisutaa) is a character in Flower, Sun, and Rain. She is a spiritual medium from the United States, who briefly stays at the Flower, Sun, and Rain hotel. She leaves on the first day of Sumio Mondo's stay on Lospass Island, explaining that she will return when her photograph is developed; however, she never does, and that is the last the player sees of her.
While she proclaims herself the best medium in the world, this is debatable as when Mondo's hotel room is transformed by a ghost, she causes a commotion over the spirit being a swirling evil force capable of possessing Mondo, when it is concluded that the spirit is in actuality a harmless ghost. While Mondo counts on her to help him with her powers, Sister Phantom disappears, having allegedly fled in a panic, although she does not admit to this when she reappears after the ghost's prank is resolved. This leads Mondo to challenge her status as a professional of her field.
It is revealed at the end of the game that Sister Phantom was hired by Tetsugoro Kusabi, possibly to locate Sumio.