Rei Batsubami, a banished former member of the Hundred Devouring Families due to a past clan conflict, arrived at Hyakkaou Private Academy presenting as male with an androgynous appearance. This initial disguise featured short brown hair with long bangs partially covering the face, dark brown eyes described as "empty," the standard male academy uniform, glasses, and white gloves. During this period, Rei served other clan members quietly and seriously, rarely speaking unless necessary, yet demonstrated unexpected compassion by protecting bullied students. This servile facade concealed a secret plot for revenge against the clan, motivated by the suffering inflicted upon Yumeko Jabami's sister. The sister had once treated Rei with kindness by gifting a dragonfly brooch, marking Rei's first positive human connection. Witnessing the sister's decline after a forced civil war orchestrated by the clan solidified Rei's resolve for vengeance, prompting the cutting of their hair. Rei initially declined gambling invitations at the academy but intervened against injustice, such as stopping bullies targeting a "pet" student. Rei also provided medical aid to Yumeko Jabami after a poisoning incident, showing protective instincts despite underlying resentments. During the student council election arc, Rei strategically organized a vote-acquisition system by collecting ballots through acts of kindness, accumulating significant influence. A pivotal shift occurred during the anonymously orchestrated Hundred Votes Auction. Confronted by Yumeko Jabami demanding to see Rei's "true self," Rei discarded the glasses, brushed back the hair, and removed the gloves, revealing tattoos of crossed-out clan symbols on both hands. This transformation altered Rei's demeanor and physicality, including a visible lightening of the eyes with distinct pupils replacing the "empty" look. Rei laid bare vengeful intentions during the auction, though Yumeko outmaneuvered the system. In a subsequent high-stakes gamble, Rei bet everything against Yumeko, culminating in a lost coin toss. Despite this defeat, Kirari Momobami acknowledged Rei's resolve and permitted reinstatement into the clan. Following reinstatement, Rei adopted a feminine appearance, wearing the female academy uniform, styling the hair more elaborately, and applying pink lip gloss. The glasses were discarded permanently, and the dragonfly brooch became a visible accessory. This phase represented liberation from servitude and vengeance, symbolizing a new identity free from past constraints, accompanied by the adoption of an undisclosed new surname. Rei's gender presentation and pronoun usage fluctuated throughout these phases. Initially referred to with male pronouns without objection, Rei shifted to female pronouns after the auction reveal. This fluidity across the banished, vengeful, and liberated phases—spanning masculine, neutral, and feminine presentations—led to interpretations of Rei as gender-nonconforming or genderfluid. Core traits include quiet seriousness, kindness toward the vulnerable, and visible confusion when receiving praise or compassion, likely stemming from lifelong treatment as an object or servant. Rei also demonstrated strategic intelligence by manipulating the clan's perception to advance the revenge plot.