Sumeragi Secret Bunker 3 is the final mission in Gunvolt Chronicles: Luminous Avenger iX.
- This stage houses the latter half of the traditional Boss rush, with Isola, Bakto, and Dystnine. Their attack patterns are identical to their original fights, with slight modifications (though not to the level of EX Bosses). They provide no unique dialogue upon encountering, winning, or losing against them. There are checkpoints and healing items provided after each Boss.
- Afterwards, it's a straight shot to the next Boss, Demerzel. Before encountering him, there's yet another healing item hidden behind a box, that can be broken with Orbital Edge.
- Demerzel has two phases, one using Asimov's attack pattern, and one using his own. They each have the same amount of health as a standard Boss, and you have to beat them both consecutively in order to continue. Both Demerzel's hologram and true form are weak to Photon Detonator. Additionally, the hologram is weak to Shroud Spear.