TV-Series
Description
Setsuna Yūki, legally Nana Nakagawa, is a second-year Nijigasaki High School student. She operates under the "Setsuna Yūki" pseudonym—borrowed from light novel characters—to hide her school idol activities from strict parents who forbid interests like anime, manga, and idols. This secret identity creates an enigmatic campus presence; Setsuna is often seen only in her idol outfit, sparking rumors and urban legends due to her perceived rarity at school. This duality exists because she attends as Nana Nakagawa, who presents distinctly: wearing glasses and styling her long bluish-dark gray hair in two low pigtail braids, contrasting Setsuna's partial ponytail with a rose ornament.

Her personality is energetic, passionate, and emotionally expressive. She lights up discussing her loves—school idols, anime, manga, and video games—frequently dedicating weekends to five hours of anime and three hours of gaming. She demonstrates deep support for friends, exemplified by repeatedly eating Kasumi's poorly made spicy bread to avoid disappointing her. As Nana, she diligently completes homework promptly and studies on off days.

Setsuna founded the original Nijigasaki School Idol Club but disbanded it after her intense passion for idol perfection caused member friction. She later rejoined the revived club when Yu Takasaki encouraged her to embrace her identity and joy as an idol. Her performances, including "Chase!" and "DIVE!", inspire others to join. She served as student council president under her real name before losing the position to Shioriko Mifune. Her family eventually discovers her idol activities, leading her mother to attend a concert and accept her pursuits.

She is a member of the subunit A・ZU・NA. Her solo songs include "CHASE!", "MELODY", "LIKE IT! LOVE IT!", and "DIVE!". She struggles with cooking, creating dishes described as "too original" in taste, and avoids health class discussions due to embarrassment. Setsuna evolves from a secluded figure balancing dual identities to someone openly sharing her passions, aiming to create a world where people freely express their loves through school idols.