Y5 appears to be an anthropomorphic humanoid rabbit with pale blue fur. Her eyes are rather unique, being white circles with a black outline on the upper half, but no outline on the lower half. She is usually seen wearing a yellow t-shirt, but in one shot she is seen wearing a white sweatshirt. She wears black leggings and teal blue boots with darker blue lines on them and white soles. She is also seen wearing a blue wristband on her left wrist with a bunny symbol on the front.
She is said to watch others from afar in their antics as a method of socializing, even with newcomers, such as the dubbed “hero”, BMO. However by the end of “BMO” she is more confident and taking charge on how to save her community in the wake of Hugo’s scheme.
- Y5 has great expertise in the field of science.
- Y5 has gravity-altering boots allowing her to walk on walls and even hang upside down.
- She appears to be the same species as Other Fionna, being a Lagomorphic Humanoid. Adam Muto has remarked on this similarity, but hasn't definitively confirmed the nature of the connection.
- She shares a number of characteristics with Finn.