Monster Association Headquarters

Nestled far below the abandoned Z-City Ghost Town, the base serves as the Monster Association's hideout and command center, and its presence is a major reason the town above sits empty. The complex is enormous, sheltering well over five hundred monsters, and Elder Centipede's tunneling links it outward to several different cities. Its true nerve center lies with Psykos, whose hidden chamber roughly fifteen hundred meters down doubles as her resting place and laboratory; from there she works her puppet Gyoro Gyoro, who in turn commands the entire Association through psychic relays planted across the base.

The stronghold rises in a mostly vertical shape, almost a tower sunk into the earth, with an endless web of tunnels and stairways stitching its levels together. Orochi's throne room forms the grand central hall, a coliseum of arena and seating where the monsters assemble for briefings and where he later duels Garou. Scattered through the maze are cell blocks for captives, mining shafts where worker monsters dig out gold and jewels along a railway, and even working toilets and elevators. Other chambers serve darker purposes: Do-S keeps a torture room lined with cages and instruments, a guarded aquarium holds the Evil Natural Water behind a door watched by Master Joe, and a storage vault packed with tanks and hoses cultivates Orochi's monster cells until Sweet Mask destroys it. Deeper still lie Psykos's furnished laboratory and the subterranean graveyard that holds the base's original owners.

The site began as tunnels carved out by the Subterranean People and the giant centipedes. Once the Subterraneans wiped themselves out in infighting after losing their king, the Monster Association claimed the vacant warren for itself, leaving the bodies of the original inhabitants entombed below. The base first draws notice during the Monster Raid, when the Association strikes the cities as cover to kidnap a sponsor's son and retreats behind Elder Centipede, downing a pursuing Metal Knight drone that Orochi strings up in the throne room. Its role grows in the Monster Association arc: Garou is dragged here after his capture, later sneaks back through a tunnel to hunt Gyoro Gyoro and save Tareo, and ends up battling Orochi in the throne room before being chained in the prisons.

The stronghold meets its end during the Hero Association's assault. The rescue team storms the surface and splits underground, and the ferocious clashes that follow, fueled by the likes of Child Emperor's Brave Giant and Overgrown Rover, tear away huge sections of the complex. Once Tareo is confirmed safe with King, Tatsumaki hoists the whole base up out of the ground, and during the showdown with the fused form of Psykos and Orochi she crushes the headquarters along with the monster, finishing off the structure for good.