The ninja blade is a weapon used by Toenail Pizza to slaughter Harry plus an army of natives, and crafted/used by a fierce Japanese warrior from ancient times named Ken Suzumaru. Toenail Pizza first obtained this weapon during the summer of 1981 from graverobbing Ken in his search for rare golden weaponry, but it was rusted badly upon repair. He thought that simply replacing the blade part would ruin the value of the sword, so he then decided to covertly travel with Michael Plumson to ancient Japan in Michael's time machine to get the sword in better condition. When there, Toenail Pizza figured out that Ken was dead at that period in time, which made his mission a lot easier. He stole the sword, and successfully made it back to 1981 without being caught by Michael. Toenail Pizza fixed the minor problems and rust of the sword after he got it, and kept a routine of doing that for the rest of his life. He also sharpened the sword, and kept a routine of doing that as well.
Like most of Toenail Pizza's other weapons, the ninja blade is made out of solid gold. Ken crafted it as a katana, because it was one of the most popular swords during his life. The blade is in flawless condition, and Michael Rosen claimed that it was "fucking sharp".