Flesh Manipulation

Seen from Chapter 2 and the second anime episode, Flesh Manipulation, sometimes called shapeshifting, is an ability every demon possesses to alter and control physical traits of its own body. In weaker demons most of these changes are involuntary, occurring during the transformation into a demon, when they sprout horns, sharpened nails, fangs, jutting veins, and a birthmark-like pattern somewhere on the body. Even so, some lesser demons exercise real control, such as the Temple Demon who grew arms where his neck belonged or the Hand Demon who sprouted and commanded many arms at once. Certain ones gain distinctive parts or animal traits, like the Tongue Demon's vase-cutting tongue or the serpentine and spider-like demons.

Growing strength, growing control

A demon's command over its flesh appears to scale with its overall power. Kyogai, a former Lower Rank, embedded drums into his body to channel his Blood Demon Art, and members of the Spider Family, fueled by Rui's blood, could spin functional silk and string from themselves. Upper-tier Twelve Kizuki demons go much further: Rui forms blade-sharp threads from his cells, Hairo turns his body into a storage space for equipment, and Enmu merges himself with something the size of a full locomotive, converting the train into his own flesh and growing tendrils to attack everyone aboard.

Constructs, weapons, and disguise

Demons like Daki and Hantengu's clones can produce clothing and accessories indistinguishable from real ones, save that they burn away in sunlight or upon death. They also forge weapons from their flesh, including a khakkhara staff, a fan, and a cross-shaped spear, each as durable as a true counterpart and repairable like any wound. Some demons mimic ice, water, lightning, or wood so faithfully that the substitutes behave naturally yet can be regenerated at will. Others adjust their apparent age despite being ageless, as Daki and Nezuko did after being turned as children. Muzan Kibutsuji's version is the most refined of all, mending entire organs so he functions with seven hearts and five brains, opening mouths along his limbs, and producing commandable copies of himself.

The ability is universal among demons, but its most striking displays belong to powerful individuals. Kyogai shapes drums, Enmu rebuilds a train, Gyutaro forms paired sickles, Nakime grows a biwa to steer the Infinity Castle, and Hantengu's clones Sekido, Karaku, Aizetsu, and Zohakuten manifest staffs, fans, spears, and daggers. Gyokko produces vases, Doma fashions golden fans for his ice, Kaigaku and Kokushibo form blades tied to their breathing techniques, and Muzan Kibutsuji exhibits the most potent shapeshifting of any demon.