Rio Futaba is a prominent supporting character in the anime series 'Seishun Buta Yarou wa Bunny Girl Senpai no Yume wo Minai'. She is a highly intelligent and reserved high school student, serving as the science club president and a close friend of the protagonist, Sakuta Azusagawa. Futaba provides scientific explanations for the supernatural phenomena that occur throughout the series, offering both logical insight and emotional support to the main characters. Her own arc deals with issues of identity and self-esteem, making her a relatable and multidimensional character.