Diana lives with her grandmother, Towa, in Arborville, a village within a Johto region forest. She is Towa's granddaughter and bears a strong resemblance to her grandmother's younger self, particularly in hairstyle, though Diana has green hair. Her typical attire includes a pink sleeveless shirt, blue jeans, white shoes, and a gold necklace. Generally more easy-going and confident than Towa, Diana becomes protective and defensive when the people or places she values are threatened. She possesses practical knowledge of the forest and its legends, such as the "Voice of the Forest" (Celebi) and the healing properties of the Lake of Life. When Celebi is critically injured and the Lake of Life becomes tainted, Diana suggests Suicune, a legendary Pokémon capable of purifying water, could cleanse the lake to help Celebi recover. During the events involving Celebi and the Iron Masked Marauder, Diana assists Ash, Misty, Brock, and Sammy. She helps rescue them using Mr. White's blimp after Celebi attacks the aircraft. Following Celebi's restoration and the defeat of the Iron Masked Marauder, Diana confronts the villain alongside Towa, Mr. White, and the forest's wild Pokémon. She is last seen waving goodbye to Ash and his friends as they depart Arborville. Diana's background is tied exclusively to Arborville and her grandmother.