Rikka Takanashi embraces intense chūnibyō, convinced her right eye holds the "Tyrant's Eye" or "Wicked Eye" (邪王真眼, Jaō Shingan), kept sealed beneath a medical eyepatch. She transforms mundane events into elaborate fantasy scenarios, striking dramatic battle poses and invoking fictional powers. Her arsenal features roller shoes enhancing mobility and the "Schwarz Shield Prototype Mark-II," a spring-loaded frilly parasol deployed as a weapon for attacks like "Gungnir" and "Dark Matter Blaze." She frequently accesses Yūta Togashi's apartment by descending from her balcony via rope. At school, she modifies her uniform with a frilly skirt and cross accessory, while her delusional activities showcase gothic lolita attire. Her theatrical demeanor contrasts with underlying clumsiness and poor academic performance. This fantasy world stems from trauma surrounding her father's sudden death two years prior. Unable to accept his loss, she crafted the concept of the "Invisible Boundary Line" (不可視境界線, Fukashi Kyōkaisen), believing it could lead her to him in another realm. Witnessing Yūta's own chūnibyō phase as the "Dark Flame Master" during junior high partly inspired this. Following her father's death, Rikka lived with strict grandparents who disapproved of her behavior, intensifying her retreat into fantasy. She later moved to her sister Tōka Takanashi's apartment, becoming Yūta's neighbor. Rikka's relationship with Yūta evolves from mutual annoyance to romantic partnership. Bonding initially over their shared delusional mindsets, they co-found the "Far Eastern Magic Napping Society – Summer Thereof" with classmates Shinka Nibutani, Sanae Dekomori, and Kumin Tsuyuri. Though Yūta initially resists Rikka's fantasies, he agrees to help her search for the "Invisible Boundary Line." This journey forces Rikka to confront her grief, culminating in her tearfully accepting her father's death. While she resumes her chūnibyō persona afterward, it becomes a healthier coping mechanism, and she openly dates Yūta. Subsequent media deepens their relationship. The OVA "Takanashi Rikka Kai" depicts Rikka dreaming of marrying Yūta and later living with him. Season 2 shows her attempting to reawaken Yūta's "Dark Flame Dragon" persona while navigating typical relationship challenges. The film "Take on Me" involves Rikka and Yūta eloping across Japan to evade Tōka's plan to relocate her to Italy. During this journey, anxiety flares when suppressing her delusions drains her powers, fearing Yūta might reject her changed self, though their bond ultimately strengthens. Yūta gives her a ring symbolizing commitment, solidifying their partnership.