Yūta Togashi is a high school student determined to leave behind his middle school past as the "Dark Flame Master," a severe chūnibyō phase where he believed he wielded dark flames and harbored a sealed Black Flame Dragon in his right arm. This persona involved dramatic spell-chanting, gothic attire with multiple belts, and declarations of world conquest, resulting in social isolation and profound shame. He enrolled in a distant high school to escape this history.

Living with his mother and younger sisters, Kuzuha and Yumeha, who witnessed his embarrassing public chūnibyō displays with confusion, Yūta exhibits housekeeping skills, helping at home and maintaining order in Rikka Takanashi's chaotic apartment. His plan for normalcy unravels when classmate Rikka, actively engaged in her own chūnibyō fantasies as the "Wielder of the Tyrant's Eye," recognizes him as the Dark Flame Master and insists on forming a contract.

Initially resisting Rikka's antics, often responding with embarrassment or light head strikes to curb her public behavior, Yūta gradually joins her quest for the "Ethereal Horizon" (不可視境界線, Fukashi Kyōkaisen), a mystical boundary she believes connects to her deceased father. Learning her delusions stem from this trauma fosters empathy, shifting Yūta from dismissal to support. By the end of the first season, he acknowledges romantic feelings, and they begin dating. This relationship challenges his aversion to chūnibyō; he occasionally indulges in fantasy role-play, participating in rituals to "awaken" the Dark Flame Dragon and later adopting the moniker "Guerzoniansus" ("Gelzoniansus" in the movie).

In the sequel season, Yūta navigates their relationship amidst Rikka's persistent delusions and external pressures, including disapproval from her family about their living arrangements. After her grandfather reverses a decision allowing independence, forcing Rikka to cohabitate with Yūta, he acts as a stabilizing voice of reason within their friend group, the Far Eastern Magical Napping Society of Summer, alongside Shinka Nibutani, Kumin Tsuyuri, and Sanae Dekomori.

The film *Take On Me* depicts Yūta and Rikka eloping across Japan to evade her sister's plan to relocate the family to Italy. During this journey, Yūta reaffirms his dedication, gifting her a ring as proof of commitment. He accepts loving all aspects of her identity, including her chūnibyō traits, culminating in their first kiss.

Yūta's personality blends diligence, responsibility, and underlying kindness with moments of hypocrisy and aggression, especially regarding his chūnibyō past. He struggles with self-awareness, sometimes dismissing others' goodwill. His character evolves from seeking normalcy to embracing vulnerability, ultimately accepting his past and present self as inseparable while supporting Rikka's emotional needs.