Itsuki Sumeragi is a supporting character in Kakegurui. She's a first-year student belonging to the "flower" class at Hyakkaou Private Academy and a member of the Student Council. Her father is the president of a prominent toy company in Japan.
She wears the Hyakkaou Private Academy issued uniform; a red blazer with black trim around the cuffs and collar that is decorated with gold buttons, underneath she wears a white button up with a black tie as well as a pleated skirt with black stockings that have silver stars on the sides of them along with a pair of brown loafers with black soles. She has blue eyes and blonde hair that comes down to her chin and bangs that reach her eyebrows. She has a green hairband in her hair. She also has pink painted nails with star-like decorations on them. In the manga, her nails are decorated with the suit of clubs.
Itsuki uses her gambling skills as well as the daughter of the president of a toy company utilizes her wealth to her advantage in order to get whatever it is she desires, whether it be a seat within the student council or even her collection of painted human nails. Equally as manipulative as she is business savvy, Itsuki uses her gambling match against Yumeko Jabami to promote her family's latest product while hiding her own secret that the cards she uses are rigged with temperature-sensitive technology that leaves her undefeated at her own game until Yumeko uncovers the truth of her deception.