During the Infinity Castle Arc, Shinobu Kocho, the Insect Hashira, enters the Infinity Castle and encounters Doma, Upper Rank Two, the demon responsible for killing her older sister, Kanae Kocho. Shinobu has a petite, slender appearance, with pale skin, large purple eyes, and short, dark-purple hair that fades into lighter purple at the tips. Her hair is tied back with a butterfly-shaped hairpin, and she wears her signature Demon Slayer uniform with a white butterfly-wing-patterned haori, a black skirt, a white belt, and white tabi socks with sandals. Her overall appearance resembles a butterfly. She uses Insect Breathing, a breathing style derived from Flower Breathing, which focuses on speed, agility, and precise thrusting attacks rather than powerful slashes. Her techniques include Butterfly Dance: Caprice, Dance of the Bee Sting: True Flutter, Dance of the Dragonfly: Compound Eye Hexagon, and Dance of the Centipede: Hundred-Legged Zigzag. She also uses wisteria-based poison in her specially designed sword to weaken demons. During the battle, Shinobu is very tense and angry toward the fight, focused and aggressive and forced herself to stay on her feet—her plan was to get absorbed by Doma because she has wisteria poison injected into her body, so if Doma absorbed her, Doma would get poisoned and it’ll be easier to chop his head off. Her movements are graceful and quick, resembling a butterfly fluttering through the air, and she refuses to let Doma’s provocations distract her from her mission. How she dies: Douma overpowers her, and created a huge slash going from her shoulder to her upper hip. Deep. Shredding her left lung, fracture her bones, and later on after her forcing herself to battle despite her major injuries, she got squeezed by Douma in a “hug” and Douma absorbed her. —- She’s known for her small figure, often feeling of jealousy of her older sister.

During the Infinity Castle Arc, Doma is an Upper Rank Two demon with a deceptively cheerful and welcoming appearance. He has long, wavy platinum-blond hair that reaches past his shoulders, with shorter strands framing his face. His eyes are rainbow-colored, with pale blue and pink tones, and his pupils contain the kanji for Upper Rank Two. He has very pale skin and usually wears a wide, carefree smile. His clothing consists of a loose, brightly colored robe with intricate patterns, an open neckline, and a large sash around his waist. He also wears traditional Japanese sandals. His main weapons are a pair of golden Japanese war fans decorated with lotus-flower designs, which he uses to create deadly ice-based attacks. During the battle inside the Infinity Castle, he maintains his friendly smile and playful mannerisms, often speaking politely while mocking his opponents. Despite his cheerful appearance, he is cruel, manipulative, and extremely dangerous. — Later in the battle, he slashed Shinobu with his fans, he gets poisoned very few times in the battle by Shinobu. —- Known for his psychotic smile. Demons can only die if they’re head gets chopped off. He’s upper two—resembling one of the strongest demons.