TV-Series
Description
Yui Goidō is a 16-year-old student at Maijima Private High School, initially presented as a girl from a prestigious family under a strict upbringing. Her mother enforced traditional expectations, demanding regular kimono wear and prohibiting her passion for drumming; this suppression created a "crevice in her heart," allowing a runaway spirit to possess her. While Yui outwardly complied, quiet resentment simmered beneath the surface.

Her journey shifted dramatically during the Body Switch Arc when an accidental body swap with Keima Katsuragi placed her in his male body. Despite initial discomfort, she adapted and seized the opportunity to join the 2-B Pencils band as their drummer, finally realizing her suppressed musical dream. This experience fostered a more assertive, masculine personality. She adopted the male pronoun "boku" and preferred wearing boys' uniforms for comfort, maintaining these traits even after returning to her original body. Her newfound confidence empowered her to openly defy her mother, reclaiming her autonomy, closing the heart's crevice, and expelling the runaway spirit.

In the Goddesses Arc, Yui was revealed as the host of Mars, one of the Jupiter Sisters. This combat-oriented goddess granted Yui superhuman strength and amplified her existing hot-headed, boyish demeanor. Mars actively supported Yui's proactive romantic pursuit of Keima. Unlike other conquest targets, Yui retained blurred memories of her past interactions with Keima, driving her to confess her love regardless of his reputation or rumors involving other girls. This dynamic sometimes disoriented Keima due to lingering physiological effects from their earlier body swap.

Serving as the 2-B Pencils' dedicated drummer, Yui consistently participated in band activities and supported allies like Elsie. Her appearance evolved from flowing tea-green hair (brown in anime) and traditional kimonos to a signature long ponytail and boys' attire, though she reverted to kimonos while sleeping. She remains the only band member not from Class 2-B and notably owned an iPhone.

During Vintage's threat, Yui collaborated with Keima to identify other goddess hosts. Mars enabled her to call out in divine language, though initial attempts targeting Ayumi and Chihiro failed. She actively participated in strategic efforts against Vintage, leveraging her goddess-granted abilities in combat.