Mayu resembles her mother more, having her skin tone and facial features, but her eyes are her father's red. Her hair is entirely Yuya's green, having an overall five-pointed star shape with two of the "points" in the front and three in the back, as if a starfish was laying on top of her head, having sidetails like her mother that look more like antennae. Mayu also wears rectangular-framed glasses that appear to have painted rims, the left rim being orange and the right rim being blue, similar to Yuya's goggles.
Mayu's primary outfit is a dark red shirt which is typically covered by the jacket ofbeing worn closed over it, a long purple skirt, white stockings under the skirt, and brown shoes. Mayu's Duel Disk is dark pink with a blue blade.
Mayu is an intellectual young woman who keeps a cool head and an analytical mind, always trying to be the sane person in the room (even if she's not the only one). However, this can sometimes make her come off as aloof or even a buzzkill (though the latter is often unintentional). Mayu gives her all to whatever she does, be it Dueling or academics, and despite a contrary upbringing, she often goes for victory rather than a good time (though she is not adverse to having fun). Like most siblings, Mayu sometimes bickers with Yuga, mainly due to him giving her grief because she isn't as fun-loving as he is, but the two of them love each other dearly and hold no grudges.
Like her parents and their counterparts, she values her friends greatly, especially the other Counterparts' Children, and she will defend them without hesitation if something happens to them. Mayu likes to keep her brain occupied, so she'll often been seen reading a book, devising new strategies with her cards, or working on brain puzzlers.
"Mayu" means "cocoon". Though her name contains the "Yu" syllable, it is not held longer like in her brother's name, similar to Yuzu's name in comparison to Yuya.
Mayu uses the formal "watashi" pronoun. When referring to how her Deck works, Mayu never considers her Deck to be a Fusion-based Deck, but rather a "Transformation Deck", and will immediately correct anyone who says otherwise.
Though Mayu is a child of a dimensional counterpart couple, it is unknown if she inherited any of her parents' powers. Unlike Yuga, she does not even seem to possess a bond with, so it will not appear in her Deck like it would for her brother.
Mystical powers aside, Mayu is a certified genius, having intelligence that far surpasses her age. As such, she is also a potent problem solver.
- Mayu's hair being analogued to a starfish on her head is a reference to the meme that her father's hair resembles a flattened starfish.
- Mayu's treatment of her Deck is an intentional inversion of how XBrain130's character, Asuyu Sakaki's, Deck is treated: Asuyu's " " Deck is clearly noted and treated as Fusion-based with no argument from her, while Mayu is adamant that her Deck is NOT Fusion-based, but merely uses Fusion Monsters. For added comedy, Asuyu's Deck gives satisfaction, while Yuri is comedically depressed when Mayu tells him otherwise.
Mayu plays a "Morphoser" Deck, utilizing "Pupa" cards on her Main Deck monsters to immediately Special Summon "Meta-Morphoser" Fusion Monsters, which Mayu adamantly refers to as "Transformation Summon". Due to the variety of her monsters and speed of Transformation Summon, Mayu can amass multiple strong monsters with ease.