Yoichi Himukai serves as a Judge in the Magic Law Association, having attended the Magic Law School alongside Toru Muhyo, Enchu, and Yu Abiko. Academically average during his studies, he frequently relied on Enchu’s assistance for coursework, forging close bonds with Muhyo, Enchu, and Biko. He later carried deep guilt for failing to notice Enchu’s despair before his friend embraced forbidden magic, causing their permanent separation. Master of all magic law branches except execution, he earned the title "Prince of Magic Law" for his strategic precision in investigations and combat. His competence clashes with overtly lecherous tendencies; he habitually gropes women, particularly targeting Nana Takenouchi while claiming to discern bra sizes through touch. This behavior coexists with fierce loyalty and emotional vulnerability, exemplified when he wept upon reading his teacher Rio Kurotori’s diary about her descent into forbidden magic. His history with Muhyo remains complex. After proposing to become Muhyo’s official partner and being rejected in favor of Jiro Kusano (Roji), Himukai developed a persistent drive to prove his worth. This fueled competitive behavior during collaborations, such as chasing Roji to recount their past with Enchu and angrily reiterating that Roji was chosen over him. Key events showcased his tactical skill and growth. During Enchu’s panic curse at school, an injury made him an early vector. In the Magic Prison arc, he shielded Biko from Rio Kurotori’s attack, erected defensive wards, and aided Muhyo’s attempt to save Rio. Later, during the Magic Law School invasion, he orchestrated counterstrategies against threats like Buhpu and the Cortlaw family, aiming to demonstrate to Enchu that redemption was achievable through lawful magic, not forbidden arts. His actions culminated in sadness over Enchu’s imprisonment in the Arcanum and a reaffirmed commitment to earn Muhyo’s partnership acceptance. He has shoulder-length black hair, often tied back with a headband, gray eyes, and typically wears a red or white shirt with black pants, switching to a black sweater and earmuffs in winter. His surname "Himukai" combines characters for "fire" and "direction," while his given name "Yoichi" blends "ocean" and "one." Outside work, he favors sandwiches, excels in sports and covert operations, and displays surprising artistic talent.