Karen Aijō, student number 1 in Seisho Music Academy's 99th Graduating Class (Actor Training Department, second year), possesses auburn hair styled in half-twintails with bangs swept to the right and red ochre eyes. She always wears a distinctive crown hairclip, a gift from Hikari Kagura, on her left bangs. Her standard school uniform is a gray blazer with dark gray trimming, gray knife-pleated skirt, white button-up shirt, red ribbon tie, brown loafers, and black three-quarter socks. Casual wear includes denim shorts, a plain white T-shirt with red hems, beige high-top sneakers, and a pale pink jacket tied around her waist. Practice attire consists of a black leotard with red straps, white tights, and a loose white shirt. Her revue outfit features a blue jacket with gold accents, a red kick-pleated skirt with a white tulle tail, black boots with gold trim, and a red pelisse jacket over one shoulder. Her weapon is a spadroon sword with a red gem at the hilt. Born in Tokyo, Karen's path to becoming a Stage Girl ignited after witnessing "Starlight" as a child alongside Hikari Kagura, leading them to vow to perform it together someday. To achieve this dream, she trained in classical ballet (since 2006), vocal music (since 2008), and modern/jazz dance (since 2010). Her youth included lead roles in productions like "Princess White Dragon" (2014) and "DREAM ~ Endless Night" (2014). After attending Meika Private Junior High School, she enrolled at Seisho Music Academy, seeking its challenging environment to hone her skills. Initially a warm, enthusiastic genki girl, Karen prioritizes friendship over competition. Her cheerful, boisterous demeanor contrasts with struggles in morning classes and academic focus, often leading to mispronounced words needing correction. Her determination intensifies dramatically upon reuniting with Hikari after a 12-year separation, reigniting her dedication to their shared promise and driving her participation in the underground revue auditions. She frequently uses the catchphrase "Non, non dayo!" and has specific habits like needing socks while sleeping to avoid cold sweats. Her favorite food is umeboshi; she dislikes green peas. Relationships are central to Karen. Her bond with Hikari Kagura forms her emotional core; their childhood promise motivates her actions, and Hikari's return restores her purpose. However, their partnership strains due to misaligned beliefs about the revue system, culminating in Hikari's betrayal during the Revue of Fate to protect Karen. Karen's roommate, Mahiru Tsuyuzaki, supports her daily life and views her as a source of brilliance. Mahiru experiences jealousy at Hikari's arrival but develops a supportive friendship with both, earning the affectionate nickname "Mamahiru." Karen also encourages Junna Hoshimi ("Junjun") to overcome fear of failure, empathizes with Aruru Otsuki's lost motivation, and nicknames Nana Daiba "Banana" for her nurturing nature, though they clash over Nana's desire to preserve the status quo. Karen's development revolves around evolving her understanding of performance and partnership. Early on, she struggles with traditional hierarchies, inviting others to share "Position Zero" instead of competing for solo glory, marking her as unconventional. Her tenacity shows in revue battles, overcoming Junna Hoshimi in the Revue of Jealousy but suffering crushing defeats against Maya Tendo and Hikari. Hikari's betrayal triggers a months-long heroic breakdown, leaving Karen listless until she reclaims her resolve to challenge the system and rebuild bonds. Achieving her dream of performing "Starlight" with Hikari leads to a new crisis; she grapples with finding purpose beyond their promise. Encouraged by Hikari, she embarks on discovering new stages and roles, like portraying King Arthur. Researching Arthur's mixed emotions upon pulling the sword from the stone symbolizes her growth from a single-dream focus to embracing multifaceted artistic challenges. Her name "Aijō" (愛城) combines "love" (愛) and "castle" (城). "Karen" (華恋) means "flower" (華) and "love" (恋), evoking the "Flora" role in "Starlight" and concepts of brilliance. Designed to start with "A" (あ) and end with "N" (ん), it emphasizes her role as the protagonist guiding the story from beginning to end.