Deep Blue is the leader of the extraterrestrials and the principal cause for their return to Earth. He submerged himself within Masaya's psyche, stripping Masaya of his memories but leaving him with a deep disdain for humanity's treatment of the environment.
In contrast to Masaya's gentle nature, Deep Blue is cold and cruel. Upon emerging, he assaulted Ichigo, injuring her arm. He disregarded Kish's plea to spare Ichigo, intent on eliminating anyone who opposed him. When Kish later challenged Deep Blue to protect Ichigo, Deep Blue swiftly killed him. This act briefly allowed Masaya's personality to resurface. Masaya managed to restrain Deep Blue from killing Ichigo again and released the final mew aqua inside Deep Blue, resulting in both their deaths but also healing Tokyo and reviving Kish along with curing the Mew Mews, Ryou, Pie, and Tart.
Although Deep Blue serves as the main antagonist, he does not make an appearance until the end of the sixth manga volume. In the anime, however, he appears as a blue light to whom Kish reports progress. In episode twenty-six, after Kish presents him with some mew aqua, Deep Blue is shown in a shadowy form until fully awakening in episode forty-nine. The manner of Deep Blue’s demise is altered in the anime, where Masaya restrains him while Mew Ichigo uses her finishing move to defeat Deep Blue and free Masaya.
To maintain the mystery around Deep Blue’s identity in the anime, he was initially credited as "Mysterious voice" with a question mark instead of a voice actor's name. After the second episode, his name appeared but the question mark remained until episode forty-nine when his identity was revealed. Then, it was updated to show Megumi Ogata as the voice actor, who also voices Masaya and the Blue Knight.
In the English adaptation of Mew Mew Power, Deep Blue retains his original name but is portrayed differently as a destructive force aiming to obliterate Earth, leading others to turn against him. In this version of the anime, he is voiced by Scottie Ray.
