Okayu has purple eyes and short purple hair with bangs reaching between her eyes and an ahoge. Being a catgirl she has cat ears, a cat tail and a cat mouth, she also wears a black animal collar on her neck.
Her original outfit consists of cropped black hoodie that shows her midriff with long sleeves that reach past her wrists, long strap-shaped drawstrings and an onigiri print on it, baggy white sweatpants (which she often wears with one leg rolled up and yellow sneakers with a cat print.
Her second outfit is a dark serafuku consisting of a cropped long-sleeved, double-breasted black blouse with white buttons and a white neckerchief sailor collar, white shorts, black socks with an onigiri print on them and black sneakers. She usually wears a black hairband with this costume.
Her New Years outfit is a wa maid-ish outfit consisting of a white kosode with the sleeves fading to purple, purple ribbon trim to the sleeves, a purple frilled skirt and a white apron with an onigiri print on the bottom right, secured with an obi-like wrap.
She's close friends with Inugami Korone, who she affectionately refers to as "Koro-san" - the loving duo referred to as "OkaKoro". She also owns a pet cat, named Temari (much to the amusement of her viewers, as a cat girl owning a cat gets quite meta).