Shoichi

Shoichi is a small boy of about eight to ten, with spiky black hair and hazel eyes rimmed in thick black, a trait he shares with both of his siblings. He dresses in a blue haori over an undyed soft-green robe, with a white layer worn beneath.

Although his character is only thinly drawn, he reads as a loyal, protective sibling who follows his older brother into danger and watches out for his younger sister Teruko. For his age he shows real courage, pushing into the haunted house after the slayers and holding steadier before the demon than the quaking Zenitsu next to him.

At the entrance of the haunted estate, Shoichi and Teruko run into Tanjiro and Zenitsu while searching for their captured brother. Suspicious at first, the children are calmed and explain the kidnapping. Told to stay outside and mind Tanjiro's box, they grow scared by odd scratching noises from within and follow the slayers inside. When the supernatural building reshuffles its rooms, Shoichi gets separated and stranded with Zenitsu.

Fed up with Zenitsu's nonstop whimpering, Shoichi chides him for being so afraid while carrying a sword. The two flee a tongue-wielding demon and are backed into a corner, where Zenitsu passes out from fright. As the creature reaches for the boy, the sleeping Zenitsu slices through its tongue and finishes it with Thunder Breathing, then wakes believing Shoichi had made the kill.

Realizing they have been going in circles, the pair hunt for a way out until a corridor tilts forward and spills them through an open window to safety. After Tanjiro frees Shoichi's older brother, the children and the slayers go their separate ways, though Zenitsu, still sure of the boy's prowess, tries to cling to him until Tanjiro knocks him out so they can depart.

Being an ordinary human, Shoichi has no special powers. The kanji of his name carry senses such as proper or correct and the number one, and the running joke about his supposed demon kill traces entirely to Zenitsu's sleepwalking feat.