Yoshino Nanase, nicknamed Yoppi, is a 16-year-old high school student from Sendai. Before joining the idol group Wake Up, Girls!, she worked as a child actress and model. Her surname means "seven rapids," and her given name signifies "good, beautiful."

She possesses fair skin, straight chin-length violet hair, and golden eyes. Yoshino stands 159 cm tall, weighs 44 kg, and has measurements of 70-58-82 cm. Her image color is light blue, and her designated animal motif is the polar bear.

Personality-wise, Yoshino presents as a "cool beauty," known for her strong sense of responsibility and maturity, qualities honed by her early entertainment career. This experience positions her as the de facto leader alongside Kaya Kikuma. She often challenges impulsive decisions by managers Kouhei Matsuda and Junko Tange to safeguard the group's stability. Her determination is evident when she rehearses and performs despite a sprained foot sustained before the Idol Festival finals, though the injury leads to a slight mishap on stage.

As leader, she is pivotal in maintaining group cohesion. Early on, she advocates for member Airi Hayashida when trainer Tasuku Hayasaka considers dismissing her. She also supports Mayu Shimada as Mayu confronts her troubled past with rival group I-1 Club, aiding her full integration into the unit. Yoshino contributes creatively, participating in collaborative songwriting for original tracks like "Polaris" during the New Chapter arc.

Following the group's establishment, she guides newer units like Run Girls, Run! by sharing insights from her journey. Throughout subsequent challenges—including venue conflicts and competition from virtual idols—she remains central to preserving the group's unity and focus on authentic performance. Her solo discography includes songs such as "Stella Drive," "Aoi Tsuki no Shangri-La," and "Dice of Life!".