The Kunai is a harpoon-like weapon used by Scorpion from Mortal Kombat onwards. Chameleon also used kunai before in Mortal Kombat Trilogy. Reptile uses this weapon in Mortal Kombat, and Smoke and Noob Saibot uses this weapon in Mortal Kombat II. According to Mortal Kombat Legacy, Scorpion was a master of the kunai. There are two kinds of Kunai: Big Kunai and Short Kunai.
The ninja spectre Scorpion chose this particular blade as his own favorite weapon in both life and death as he continued to use it in battle and even slaughtering his foes and anyone who dared to get in his way throughout the entire Mortal Kombat legacy, especially when he shouts his famous catchphrase "Get over here!" as he pierced his opponents with this attack.
The weapon had evolved over the years; first with the Kunai attached to a rope, then with the Kunai attached to a metal chain. However, in the Mortal Kombat film continuity, including Mortal Kombat: Conquest, Scorpion's "spear" is a sentient, serpent-like being that emerges from a hole in his palm and strikes at his command.
The kunai itself has also appeared as another collectible Relic named "Scorpion's Spear" within the Konquest mode of Mortal Kombat: Armageddon. In Mortal Kombat (2011), Skarlet has four short kunai on her right leg, which she can throw and attack her enemies with in kombat.
In Mortal Kombat X, Scorpion's apprentice, Takeda Takahashi, uses explosive kunai in battle. Along with this, Takeda uses serrated edge Whips with a kunai at their end to pull his opponents toward himself to inflict further damage, much like his master.