The phantom Aqua is an antagonist introduced in Kingdom Hearts 0.2 Birth by Sleep -A fragmentary passage-. She is the personification of Aqua's doubts and insecurities, and is encountered in the Realm of Darkness.
When Aqua reaches the remnants of Dwarf Woodlands, she finds a mysterious mirror. Her reflection comes to life and pulls her inside its mirror realm, where her true reflection is stolen by three identical magic mirrors. As Aqua explores this realm in order to escape, the phantom Aqua taunts her by claiming that her actions are futile and that nobody cares about her. Each time Aqua locates one of the three mirrors, a phantom Aqua attacks her, but is defeated. Once the third phantom Aqua is destroyed, Aqua is able to escape the realm and continue her journey, but its taunts continue to pain her.
The phantom Aqua is physically identical to Aqua. However, unlike Aqua, the phantom Aqua has lighter blue eyes.
As a copy of Aqua, the phantom Aqua has all of the real Aqua's abilities, even wielding a copy of the Master's Defender Keyblade. In battle, the phantom Aqua teleports, creates doppelgängers, and spawns large ice crystals to attack her enemies. The phantom Aqua can also use the Spellweaver Command Style.