Haruka appears as a main character in "Pokémon: The Mastermind of Mirage Pokémon," traveling with Ash, Brock, and Max after receiving Dr. Yung's invitation to his laboratory. At the Mirage Mansion, they join Professor Oak and Misty. During Dr. Yung's demonstration, the Mirage System generates holographic Pokémon, including extinct species like Kabutops and Armaldo. Dr. Yung challenges Ash and Haruka to battle a Mirage Aggron. Haruka accepts first, sending Staryu against Aggron. Staryu's attacks fail as Aggron uses unexpected moves like Thunder Wave and Bullet Seed, defeating Staryu and revealing the Mirage Pokémon's unique threat.

When the system malfunctions and is hijacked by the masked "Mirage Master," who captures Dr. Yung and Professor Oak, Haruka helps devise a rescue plan. She and Ash infiltrate the castle from below, swimming through an underwater opening using Staryu and Ash's Corphish. Inside the basement, they unexpectedly encounter Team Rocket, also seeking the Mirage System. Security cameras alert the Mirage Master, who dispatches Mirage Pokémon to attack. During the ensuing chaos, Misty is knocked off a platform but rescued by Haruka and May, who entered after seeing an explosion.

Haruka, Ash, May, and Max later confront the Mirage Master outside the castle after he expands the Mirage Field. Haruka sends her Gyarados to battle the Mirage Master's creations, including Mirage Mewtwo and Mirage versions of Entei, Articuno, and Zapdos. Gyarados fights alongside Ash's Pikachu, May's Combusken, and Professor Oak's Dragonite, but they are overwhelmed by the Mirage Pokémon's strength. Throughout these events, Haruka demonstrates courage and teamwork, actively battling Mirage Pokémon and aiding rescue efforts, utilizing her skills as a Water-type Trainer during the underwater infiltration and combat.