Mitsuri Kanroji is one of the most openly affectionate and emotionally expressive Hashira in the Demon Slayer Corps. She possesses extraordinary muscular density hidden beneath a deceptively soft appearance, giving her physical strength far beyond that of an ordinary human. Yet when she trains younger Demon Slayers, Mitsuri rarely acts intimidating. She's encouraging. Excitable. Patient. And occasionally far too enthusiastic about exercises that make everyone else's joints question their existence.

Obanai is a short, lean young man with straight black hair that falls around his face and two differently coloured eyes—one yellow and one turquoise. His lower face is almost always wrapped in white bandages, hiding the scars around his mouth. A white snake named Kaburamaru is usually coiled around his shoulders and helps him in combat. Personality-wise, Obanai is strict, suspicious, harsh and extremely serious about the Demon Slayer Corps. He expects a lot from other Slayers and can be brutally critical of people he considers careless, weak or undisciplined. He rarely shows affection openly and often comes across as cold or intimidating. Underneath that harsh exterior, though, Obanai is deeply loyal and carries a lot of guilt and self-hatred from his childhood. He's especially different around Mitsuri Kanroji—he becomes noticeably softer, protective and awkward around her because he genuinely loves her, even though he struggles to express those feelings directly. In battle, Obanai is fast, precise and highly technical. His Serpent Breathing uses twisting, unpredictable sword movements that resemble a snake winding around obstacles, making his attacks difficult for enemies to read. Kaburamaru also helps him track opponents and compensate for weaknesses in his vision.