Nobara's Powers In Jujutsu Kaisen Explained

During her first fight in Episode 3, Nobara reveals that her primary weapons in combat are a hammer, some nails, and a straw doll. Viewers with knowledge of Japanese folklore will recognize these as implements used in a voodoo-like spell called ushi no koku mairi, performed by nailing a straw doll to a tree (via Yokai.com). While broadly considered black magic, its effects can vary depending on whomever is performing the ritual.

Nobara, meanwhile, forgoes the need for a tree, while using each other core component of ushi no koku mairi to great effect in battle. In her combat debut, Nobara demonstrates how she can imbue her nails with cursed energy, such that, when struck in midair with her hammer, they become deadly projectiles capable of puncturing Curses' bodies.

She then expands on this technique in her fight with the witchlike Momo Nishimiya in Episode 17. One of Momo's signature attributes is her speed, enhanced by a witch's broom that grants her the power of flight. During their battle, Nobara fires a series of nails into the forest that surrounds them, all of which miss the speedy Momo and instead land in various trees. However, this is but a prelude to the activation of her Hairpin technique, which causes each of those nails to explode in bursts of Cursed Energy. Her nails alone, then, are multi-use projectiles capable of piercing her enemy's flesh or turning into powerful explosives.