The Inverted Spear of Heaven is a dagger with a jutte-like shaped blade. It has a "q"shaped circular hand guard that points out on the side of the longer blade. Additionally, the weapon has a black handle with a circular link at the end that allows it to be connection to metal chains.
It has been imbued with a cursed technique powered by a special foreign type of cursed energy that allows it to force the stoppage of any other technique it comes into contact with. If a user's target or their jujutsu is hit by the Inverted Spear of Heaven, it will be immediately nullified. Even powerful cursed techniques like the Limitless can be completely stopped by this weapon.
Toji Fushiguro possessed the Special Grade Cursed Tool: The Inverted Spear of Heaven and kept it within his inventory curse with the rest of his cursed tools. This allowed him to take out the Inverted Spear of Heaven at any time. He did so during his first battle with Satoru Gojo. Satoru immediately knew Toji was plotting something sinister as soon as he pulled out the cursed tool.
Toji was able to finish his first fight with Satoru by getting in close and stabbing clean through his throat, completely negating the "Infinity" ability of the Limitless. Then he simply slashes Gojo's body to ribbons using the cursed tool and a smaller knife, leaving the sorcerer in a pool of his own blood.
Against Suguru Geto's Kuchisake-Onna, Toji used the dagger with great speed, deflecting all of her scissor blades in an instant despite most of them being extremely close to snipping his body. He finishes of Suguru by slashing him with another cursed tool before defeating him with a blunt strike from the Inverted Spear of Heaven, purposely knocking him unconscious.
In Toji's final battle with Satoru, he connected the Inverted Spear of Heaven to a very long kusagari (鎖分, "metal chain") to utilize the dagger as more of a kusarigama-like weapon.
He believed at even long range he could nullify Satoru's Red and Blue Limitless techniques using the cursed tool's extended reach. In his last effort to strike down Satoru, Toji creates a shockwave of rubble and dust using the chained weapon to hide its approach toward Satoru in the air. It came quickly enough for Satoru to be unable to dodge it while levitating, but he was able to counter by striking Toji directly, ending their fight.
- This weapon is based on the Ama no Sakahoko spear from Japanese mythology.