Honoka Kōsaka attends Otonokizaka High School as a second-year student. Her family runs Homura, a traditional Japanese sweets shop, where she lives with her parents and younger sister Yukiho. Both her grandmother and mother graduated from Otonokizaka Academy. Childhood friendships define her early years: she bonded with neighbor Kotori Minami through their mothers' connection and met Umi Sonoda during hide-and-seek. At school, she knows Fumiko, Hideko, and Mika.

Driven by relentless optimism and high energy, Honoka embraces risks and pursues goals with unwavering determination, sometimes pushing herself to exhaustion. This resolve sparked the creation of the school idol group μ's. Though impulsive and occasionally clumsy, she counters setbacks with positivity. Despite her family's profession, she dislikes red and white bean paste, preferring strawberries and bread. She enjoys swimming, collects stickers, and credits good fortune for her uncanny ability to find money on streets.

Facing Otonokizaka's closure due to low enrollment and inspired by idol group A-RISE, Honoka conceived μ's to boost the school's visibility. She recruited Kotori and Umi first, expanding to nine members while overcoming membership quotas and institutional resistance. In the manga, she named the group; the anime credits Nozomi. Her enthusiastic, charismatic leadership made her μ's primary center. Later, she succeeded Eli Ayase as student council president.

Honoka confronts self-doubt and leadership pressures throughout her journey. Early struggles include a tearful manga debut performance and academic challenges requiring remedial tutoring. She gradually balances impulsivity with responsibility, especially as president. Her growth peaks when μ's wins the Love Live! competition. The group disbands after their Tokyo Dome finale in the movie, where Honoka motivates others through the transition with characteristic resilience.

Her legacy persists in spin-offs. *School Idol Festival All Stars* shows her collaborating with fellow idol leaders and competing in events like "μ's vs. Nijigasaki." *Love Live! Sunshine!!* references her impact through a cameo where a similar-looking child inspires Chika Takami.

Distinct traits include her signature right-side ponytail, originally styled by Kotori in childhood. Her official image color is orange, though stage costumes often feature pink. She frequently wears practice shirts marked "ほ" (ho). In elementary school, she favored milk; currently, she skillfully makes rice cakes.