Seiji Matoba leads the powerful Matoba exorcist clan, renowned for its strength and contentious practices within the spiritual world. He has long black hair, black eyes, and consistently wears an eyepatch over his right eye to hide a scar. This injury results from an ancient family curse: an ancestor pledged his right eye to a youkai for aid but broke the promise, leading male clan heads to be targeted for their right eye. The eyepatch serves as a protective talisman, causing him depth perception difficulties. Matoba displays a complex personality blending pragmatism and ruthlessness. He prioritizes safeguarding humans yet readily sacrifices weaker youkai as bait to trap stronger entities and eliminates human obstacles without hesitation. He treats youkai as expendable tools, favoring archery and purification spells over sealing. Despite this cold approach, he exhibits unexpected flexibility, particularly towards Takashi Natsume. After initially mistaking Natsume for a youkai and attacking him, Matoba develops a persistent interest upon learning Natsume is the grandson of formidable exorcist Reiko Natsume. He repeatedly attempts to recruit Natsume into the Matoba clan, citing protection from spiritual threats and acknowledging his latent power. His background reveals exceptional early spiritual prowess. Born the Matoba family's second child, he was not the initial heir; his elder sister Shinobu received that training. Succession conflicts emerged as they matured, culminating in Seiji being named future head due to superior abilities—a decision prompting Shinobu's departure and creating lasting sibling tension. During high school, he met fellow exorcist Shuuichi Natori at a spiritual gathering, tested Natori's abilities, and initiated their future adversarial relationship marked by distrustful cooperation during professional necessities. His development shows evolving dynamics, especially concerning Natsume. Matoba shifts from manipulative tactics—like threatening to expose Natsume's spiritual abilities to his foster parents—to demonstrating genuine trust, such as accepting Natsume's explanation about losing an important letter without question and writing unusually detailed correspondence to aid cooperation. He displays protective instincts, rescuing Natsume and Madara from danger without immediate benefit, and offers subtle kindnesses like tea during tense meetings. These interactions suggest underlying respect for Natsume's principles despite their persistent ideological clash over youkai treatment and exorcism ethics. Matoba wields considerable spiritual power, perceiving youkai and employing advanced exorcism techniques. He specializes in archery, often dispatching threats with single arrows, and commands extensive knowledge of sacred sutras, sealing rituals, and purification spells. His shikigami servants, including primary assistant Nanase, execute missions and gather intelligence, extending his operational reach. His relationships extend beyond central figures; he maintains professional ties with exorcist Ban (who serves Shinobu) and acknowledges acquaintances like Tooru Taki's grandfather through formal visits. As events unfold, Matoba's motivations reveal deeper complexity beyond clan interests. His focus on Natsume evolves from a utilitarian assessment of power potential to personal investment, shown through observations about Natsume's loneliness and physical well-being. While maintaining antagonistic methods, his actions increasingly reflect a desire to reshape exorcist traditions and protect talented individuals who challenge established norms.