Myu is a small, mascot-like angelic being who resides within the giant cyborg white whale that serves as the central vessel of the Mu forces. Possessing a cherubic and innocent appearance, Myu functions as a companion and guide within the whale, and according to the character Madora, Myu knows everything about the white whale itself, including its systems and history. This deep knowledge makes Myu an invaluable source of information for the five young warriors from Mu as they battle the resurrected Atlantis empire.

Myu's personality is childlike and gentle, communicating in a simple, toddler-like manner, often punctuating speech with meowing sounds such as "mew, mew." This endearing and playful way of speaking contrasts with the serious and high-stakes conflict between Mu and Atlantis, providing a softening presence aboard the whale. Myu's primary motivation appears to be supportive, helping the warriors understand the white whale and aiding their mission to defend Earth from the Atlantean invasion. Myu is not a combatant but rather an informational and moral support figure, closely associated with the white whale itself and by extension with Madora and the prophet Ramu, whose brain is housed within the whale. Throughout the story, Myu remains a constant, loyal presence on the whale, offering knowledge and companionship to the young heroes as they develop their abilities and grow into their roles as defenders of Earth. Notable abilities include an encyclopedic knowledge of the white whale and its functions, as well as the ability to communicate in a simple, accessible manner that reassures and informs the team.