Zay has an androgynous, stocky-yet-rounded appearance, due to being a fusion of two males and two females. They have long, messy, dark maroon hair with green highlights. On the left side it is tied in a pigtail with Rito's green elastic, while on the right side it comes down freely. Their eyes are mostly golden but fade to purple on the upper edge, and the right pupil is slit-like.
Zay wears a chaotic mash-up of their components' clothing: Yushi's brown t-shirt stitched to the sleeves of Runo's pink riding suit with green lines and orange pads, Rise's blue shirt-shaped cape clipped to the shoulder pads, Runo's pink gloves, Rito's yellow skirt morphed into tight shorts, and Rise's boots.
Zay alternates irregularly between "I" and "We", due to imperfect merging of the components' personalities, which are still retained in a state of shared semi-consciounsness differently to Zarc.
Zay's personality is complicated, and exhibits traits traceable to their components. Usually Zay acts a single individual (signified by the usage of "I"), but under stressful or difficult condition the different children de-synchronize (switching to "we"), and Zay may appear to start arguing with themselves. If they don't manage to get a hold of themselves and agree how to proceed in these cases, Zay can spontaneously split apart.
Zay possesses both dark powers and nature powers, gained from their components, who in turn inherited them from their parents. With a bit of strain on themselves, they can use both of them in balance.
"Zay" is a portmanteau of "Zarc" and "Ray".
- Many traits of Zay were inspired by the potrayal of fusion between characters in the cartoon Steven Universe, in particular Stevonnie, the fusion between the protagonist Steven Quartz Universe and his best friend Connie Maheswaran.