Seeds of Doubt

Seeds of Doubt is a hidden trophy/achievement in the Zombies map Zetsubou No Shima that appears in Call of Duty: Black Ops III. It is the main easter egg of the map, and it requires the player to "save" the original Takeo Masaki. Much like the Origins and Der Eisendrache easter eggs, it is entirely possible to complete this easter egg in solo.

Prerequisites
Before starting the easter egg, the player must obtain the following items:
 * Anywhere But Here! GobbleGum
 * Skull of Nan Sapwe
 * KT-4 & Masamune (Upgraded KT-4)
 * Gas Mask
 * Zombie Shield
 * 1 Bucket
 * 1 Seed

Step One: Revealing the Elevator Shaft
Once the players have obtained the Skull of Nan Sapwe, a player must go down to the Living Quarters in the Bunker and go over to where the purple water is. Using the skull, the player must mesmerize a piece of paper on the wall across from the purple water. This will now allow players to remove secret doors hidden on the map.

Step Two: Unlocking the Generator Room
Across from the door leading to the Anti-Aircraft Platform is a door which can be opened using the Skull of Nan Sapwe. The player must mesmerize the door, which will disappear, revealing a generator.

Step Three: Gathering Cog #1
With the KT-4, the players must shoot the blue cobwebs behind the blue water pond, revealing a secret cave. Inside the cave will be a massive spider boss. Players will need to shoot its mouth while it is vomiting. Every so often, the Giant Spider will summon smaller spiders and one of them will drop a Max Ammo after being killed. After killing the Giant Spider, the player must use the Anywhere But Here! GobbleGum from within the cave, which leads to teleporting to a secret room above Lab A. There, the player can find one of the three cogs on the ground. The player can then pick up the cog and can either use the Anywhere But Here! GobbleGum or use the hole in the side of the wall to exit the room.

Step Four: Gathering Cog #2
For this step, the player must have a bucket and at least one seed. Planting the seed and watering the plant with blue water, the player must shoot the watered seed with the KT-4 and repeat this two more times in the next two rounds before the plant will grow into a purple pod with yellow spots. Opening the pod will reveal a missile which can be inserted in the FlaK 88 cannon at the Anti-Aircraft Platform. Once the missile is in the cannon, the player must wait for a cargo plane to fly over the map. When the plane is in sight, the player must hold the action button on the FlaK 88, which will launch the missile at the plane, destroying it. Once the plane is destroyed, the cog can be located outside the entrance to the Bunker, by the meteor by Lab B or by the staircase leading up to the Zipline by Lab A with smoke emitting from it. The cog can then be picked up by the player.

Step Five: Gathering Cog #3
In order to complete this step, all players (or just the player if playing solo) must complete all their challenges located at the area where the skulls can be found. Once all the challenges are done, lightning will strike the platform periodically. To do this step, the player must hold out the Zombie Shield while the lightning is affecting the platform. Once done, the player must head over to the top of the Zipline located in Lab A. In co-op, another player must be waiting down at the bottom of the Zipline at the Docks. The player at the top must melee the Zipine control panel with the electric shield and then use it. When the player is over a lone dock, the player at the bottom of the Zipline with the other electric shield must melee the other Zipline control panel just as the player is over the dock, which will cause the player on the Zipline to drop down from the Zipline onto the dock, where the third cog can be found. On solo, the player must shock the Zipline control panel at Lab A and use the Zipline. When the player is over the dock, the player must lean back by pulling back on both of the joysticks on the controller, which will cause the player to drop onto the dock. If the player misses, the result will be falling into a death zone and immediately dying.

Step Six: Activating the Secret Elevator and Clearing the Vines
Once all three cogs are collected, bring the cogs to the generator in the secret generator room and hold the action button on the generator, which will reveal a secret elevator. Before going down, the player must have a Gas Mask equipped and have the KT-4 upgraded into the Masamune. All of the players must go into the elevator and use it, which will then take them to a secret part of the Bunker. Once the players reach the bottom, the player with the Masamune must shoot the three vines in the path leading to a door at the end of the hallway.

NOTE: Before going down the elevator, make sure all players have a Gas Mask equipped, otherwise players will die at the bottom of the elevator.

Step Seven: Battling the Giant Thrasher
Once the players enter the door, a massive Thrasher can be found in a giant cage. In order to start the final step, the player with the Masamune must shoot the spore on one of the Giant Thrasher's arm, which will begin the boss battle. There, the players must survive an onslaught of zombies, spiders and Thrashers before another spore will appear on one of the arms of the Giant Thrasher. The player with the Masamune must shoot the spore and repeat the process until the Giant Thrasher is killed. Once it is killed, the end cutscene will activate for the players, which shows WWII Takeo in a cage, followed by an end to the easter egg and unlocking the achievement.

Trivia

 * Upon completion of the easter egg, all characters will now possess two blood vials on their character model.
 * The XP reward title for this easter egg is "Horticultural Heroism".