Obanai Iguro serves as the Serpent Pillar within the Demon Slayer Corps, shaped by a harrowing past. His birth into a clan that venerated a serpentine demon subjected him to years of brutal confinement and ritualistic abuse. Designated as the first male sacrifice in centuries, he endured forced overfeeding and facial mutilation at twelve, his mouth slit ear-to-ear to mimic their deity—scars perpetually veiled by bandages. A white snake, Kaburamaru, emerged as his solitary ally in captivity, later evolving into his battle companion and sensory guide. Fleeing his clan with Kaburamaru’s aid, Obanai faced pursuit by the serpent demon until Flame Hashira Shinjuro Rengoku intervened. The demon’s subsequent massacre of his clan spared only a resentful cousin, cementing Obanai’s guilt-driven resolve to eradicate demons. His stern demeanor masks profound self-loathing, manifesting in relentless discipline toward himself and others. He chastised Tengen Uzui for retiring post-injury, asserting Hashira must fight until death, and during training, bound lower-ranked slayers as obstacles to instill resilience. Loyalty to Corps leader Kagaya Ubuyashiki anchors his purpose, while concealed affection for Mitsuri Kanroji drives quiet acts—gifting green socks, shielding her fiercely. Believing himself tainted, he vowed to confess his feelings solely in a reincarnated life free of demons. In battle, Obanai wields Serpent Breathing, a style mirroring a snake’s fluidity, executed via a coiled Nichirin blade. Kaburamaru augments his partial blindness by detecting threats, enabling precision strikes like Winding Serpent Slash and Venom Fangs of the Narrow Head. Confronting Muzan Kibutsuji, he awakened a serpentine Demon Slayer Mark, amplifying his agility. Though fully blinded mid-battle, he relied on Kaburamaru’s guidance, ignited a crimson blade to hinder Muzan’s regeneration, and fought relentlessly. His arc traces gradual vulnerability: initial distrust of Tanjiro and Nezuko softened into gratitude during Muzan’s defeat, while guarded exchanges with Mitsuri shifted to overt protectiveness during clashes like the Nakime confrontation. Mortally wounded, his final act entrusted Kaburamaru to Kanao Tsuyuri, echoing his yearning for rebirth into peace.