History Anime / DecaDence

In reality, in the latter part of the 25th century, air pollution had reached lethal levels and society broke down. In the midst of all this, large {{Mega Corp}}s took over and developed cyborg bodies that quickly came to outnumber humans. Eventually, one of these corporations acquired the rights to the remaining unmodified humans, putting a gigantic dome over the continent of Eurasia and making it a wildlife preserve for humans with its own self-governing system... [[TrumanShowPlot and an entertainment facility for cyborgs]]. With humans none the wiser, they had become the {{NPC}}s in a bizarre mix of {{LARP}}ing and [[VirtualReality VR]] {{MMORPG}}, with Gadoll being genetically-manufactured monsters created to keep things interesting and Gears actually being the human avatars of cyborgs who now reside off-planet. Kaburagi is one such cyborg, a retired top player turned MMO-Cleaner who was days away from [[DrivenToSuicide depleting his real body's power core and deleting himself]] before discovering that Natsume is actually a "bug" in the system; in this case an {{Unperson}} whose embedded tracking chip broke down shortly after the Gadoll attack that took her father and arm. But rather than kill her as per company policy, her strange existence renews Kaburagi's interest in the game and he decides it would be far more interesting to take her on as an apprentice. What follows throws the intended "storyline" of the game going completely off the rails, for better or for worse.

* MixAndMatchWeapon: The main weaponry of Gears and Tankers are various weapons that function like a HarpoonGun and PileBunker combined. The weapons were essentially made to launch large metal needles that are hollow inside so that when they are successfully penetrated in a Gadoll's flesh, it can drain the blood out of it like a syringe. The blood is then absorbed into the fuel packs of the Gears and Tankers to allow them constant flight in the Gadoll's zero gravity zone. The weapons come in different sizes and shapes such as {{Arm Cannon}}s, BladeOnAStick, and so on.

In reality, in the latter part of the 25th century, air pollution had reached lethal levels and society broke down. In the midst of all this, large {{Mega Corp}}s took over and developed cyborg bodies that quickly came to outnumber humans. Eventually, one of these corporations acquired the rights to the remaining unmodified humans, putting a gigantic dome over the continent of Eurasia and making it a wildlife preserve for humans with its own self-governing system... [[TrumanShowPlot and an entertainment facility for cyborgs]]. With humans none the wiser, they had become the {{NPC}}s in a bizarre mix of {{LARP}}ing and [[VirtualReality VR]] {{MMORPG}}, with Gadoll being genetically-manufactured monsters created to keep things interesting and Gears actually being the human avatars of cyborgs who now reside off-planet. Kaburagi is one such cyborg, a retired top player who was days away from [[DrivenToSuicide finishing starving himself to death]] before discovering that Natsume is actually a "bug" in the system; in this case an {{Unperson}} whose embedded tracking chip broke down shortly after the Gadoll attack that took her father and arm. But rather than kill her as per company policy, her strange existence renews Kaburagi's interest in the game and he decides it would be far more interesting to take her on as an apprentice. What follows throws the intended "storyline" of the game completely off the rails, for better or for worse.

* {{Kaiju}}: The gigalind of the first episode looks like a land whale with the shell of a sea snail that's nearly as big as the whole Deca-Dence.

* SelfDestructMechanism: The Gadoll manufacturing plant has a kill-switch that will destroy all gaddoll currently active in the game, probably as a safety measure if the Gears are somehow unable to hold back the tide and Deca-Dence the vehicle is in danger of serious damage. [[spoiler:Kaburagi and Natsume activate it as part of their war against the gadoll and by extension, the System.]]

* MasculineFeminineAndrogyneTrio: Mindy, Mundy and Mendy, the recurring triplets. Mundy is a muscular man. Mendy is a petite woman wearing pigtails. Mindy is muscular with short short hair and a face closer to her brother's, with her tip-offs of being female being her chest, emulating her sister's BareYourMidriff style and her voice.

* BareYourMidriff: Some women, like Linmei, are seen with shirts that expose their navels.

* CrapsaccharineWorld: The world outside the "Zone" is actually a colorful dystopian hell utterly controlled by corporations, with the Zone itself used to give their cyborg workers an out for the obscene amounts of stress they're put under.

* OffTheRails: InUniverse, Kaburagi derails the admins' planned storyline by [[spoiler:killing the Gadoll Alpha at Mt. Everest, which was supposed to be a HopelessBossFight.]]

* YouGottaHaveBlueHair: Linmei has purple hair while Fennel has green hair.

* GenreShift: [[spoiler:The game Deca-Dence changes genre by the end of the story, with no more Gadoll to fight, it goes from an Action RPG MMO to a family-friendly game which includes actions like minigames, non-fatal fights, exploration, and farming.]]

Produced by Studio NUT, the series is directed by Yuzuru Tachikawa (''Anime/DeathParade'', ''Manga/MobPsycho100'') and aired during the Summer 2020 anime season. The show is licensed in North America by Creator/{{Funimation}}.