Great Serpent is a gigantic white snake with a tan yellow underbelly. Like most of the ten shadows shikigami, the snake has black markings all over its body, including a symbol on its forehead. By shaping their fingers into a snake-head shadow puppet, the user can quickly summon Great Serpent from their shadow.
Megumi used Great Serpent to neutralize large curses that were close to killing his ally, Nobara. Great Serpent attacked the fungus-like by biting into it while Megumi's Toad secured the girl.
In his fight with Sukuna, Megumi used Great Serpent's quick summon to his advantage. It served as an effective surprise attack that caught Sukuna in the snake's mouth and held him immobile high in the air. This allowed Nue to repeatedly strike Sukuna while he was bonded. However, Sukuna escaped moments later, ripping Great Serpent apart and completely destroying the shikigami.