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The subject of this article appeared in Call of Duty: Black Ops III. The subject of this article appeared in Zombies mode

"AHAHAHAHAHA! Do you hear the sound of thunder?!"
Richtofen when killing Zombies with the KT-4.

The KT-4, also known as the Kusanagi-no-Tsurugi, is a buildable Wonder Weapon that appears in the map Zetsubou No Shima. It fires a green liquid that causes spore bags to grow on standard zombies before exploding, it causes Thrasher spore bags to pop and will instantly explode Spiders. This liquid also can effect the various fauna of the map, with the projectile acting as fertiliser for the Seeds and causing the spore bags to produce blue spores which temporarily increase speed along with increased sprint duration, at the cost of a much extended rest time.

These shots can be charged up to three times, which causes the liquid to remain on the floor, bubbling and affecting any zombie that goes over it. This charge can be cancelled by meleeing.



The KT-4 can be found in the Bunker but requires unique ammo that needs three ingredients to be crafted. The ingredients are:

KT-4 Vial Piece BO3.png A randomly spawned scientist zombie will be glowing a sickly yellow/green and will drop the vial upon death.
KT-4 Venom Piece BO3.png Within Lab A, with the power restored there is a cage that can be lowered down into the swamp below, doing so will open it up, revealing an arm that is producing a purple mist. This can be used to trap a Spider in by luring one close to the cage. With a spider in the cage, returning the cage back up to the lab will cause a nearby syringe to extract a vial of venom from the spider, killing it in the process.
KT-4 Plant Piece BO3.png Located in the flooded section of the Bunker Laboratory at the end of a tunnel of raw Divinium.

With the ingredients in tow, they can be mixed in the KT-4 bench, allowing the KT-4 to be picked up and to start spawning in the Mystery Box.


The KT-4 cannot be upgraded via the Pack-a-Punch Machine but requires a more potent ammo to be crafted in the secondary bench. The ingredients for that are:

Liquid Divinium Vial BO3.png With a electrically charged Zombie Shield obtained from being struck by lightning hitting the completed Trials of the Ancients altar, the cage within Lab B can be opened by meleeing the control panel. Entering the cage will lower down into the swamp before opening up the panels below, revealing a small area that houses multiple skeletons, one which is holding a vial of liquid divinium.
KT-4 Venom Piece BO3.png Upon killing the Giant Spider, their fang can be removed by interacting with the corpse.
KT-4 Plant Piece BO3.png The Skull of Nan Sapwe is required to unlock a hidden Seed planter beside the original plant location. Mesmerising the wall beside it will reveal the planter. However it also needs a unique type of water to feed it. This water can be located within the Sewer Pipe fast travel by some raw Divinium on the right side, this water can be identified by shining incandescently in the bucket. The plant must be watered three times over three rounds to sprout the unique plant.

These can be processed in the other bench to create the ammo utilised in the Masamune.

KT-4 vs Masamune

KT-4 Masamune
KT-4 BO3.png Masamune BO3.png
Fire mode Semi-automatic
2-3 round charges
2-3 round charges
Magazine size 6 6
Max ammo 36+6 36+6
Mobility Moderate Moderate
Extras 5 seconds longer chain effect



  • Seeds of Doubt (75Gamerscore.png/Silver TrophySilver Trophy PS3 icon.png) - In Zetsubou No Shima, the one must be saved.
  • Herbal Remedy (20Gamerscore.png/Bronze TrophyBronze Trophy PS3 icon.png) - In Zetsubou No Shima, use a plant to return to life.
  • Crop Duster (15Gamerscore.png/Bronze TrophyBronze Trophy PS3 icon.png) - In Zetsubou No Shima, kill 10 zombies with a single shot of the KT-4.
  • Web of Defeat (5Gamerscore.png/Bronze TrophyBronze Trophy PS3 icon.png) - In Zetsubou No Shima, remove webs in every possible way in one game.


  • The full name of the weapon, Kusanagi-no-Tsurugi, is also known as the name of a legendary Japanese sword, one of the three Imperial Regalia of Japan. Its upgraded form, the Masamune, is also the name of a legendary Japanese swordsmith.
  • On the side of the KT-4, there reads "731細菌戦の研究機関", roughly translating to "Research Institution 731 of Bacterial Warfare". This is a reference to Unit 731, a Japanese covert research group on whom Division 9 is based.
  • The KT-4's serial number is 02182016 and Masamune's is 03182016.