Source plot synopsis — includes the ending
The game opens with Gunvolt assigned on a mission to assassinate an adept named Lumen. He is told that Lumen has the ability to resonate with and control any adepts through her singing, and is considered dangerous. However, Gunvolt discovers that Lumen is the septimal projection of a young girl named Joule, who is a captive of Sumeragi's scientists, and can't bring himself to kill her. He instead rescues her, leading him to amicably defect from QUILL and set out on his own to protect her. He becomes a freelance agent, but still works jobs for QUILL from time to time.
Six months after defecting from QUILL, Gunvolt is offered a freelance assignment by Moniqa, his handler from QUILL, to investigate and take out several agents of the Sumeragi Group. The Sumeragi agents are all adepts as well, but powered by strange Glaives, which house their septimal essences, and are representative of each of the Seven Deadly Sins. The first agent, Merak, is a lazy, unenthusiastic adept with the power to bend space for use in his attacks. The second, Jota, is a prideful agent with the power to manipulate light. The third, Viper, is loud, brash, and violent, has control over fire, and harbors a jealous rage against Gunvolt for Joule. The fourth, Carerra, uses magnetic fists and waves to draw his enemies close before destroying them with a powerful pulsewave. The fifth, Elise, is a split personality adept: her meek, timid side and her brash, assertive side are at constant odds, but her ability to raise the dead allows for even adepts to come back from defeat. The sixth, Stratos, is a drug-addicted adept with an insatiable hunger for the very drug that keeps what little of his sanity remains in check, and has control over swarms of insects. The seventh, the carnal Zonda, attacks and wounds Zeno, one of Gunvolt's friends from QUILL, but is seemingly killed by a human warrior named Copen, who harbors a major hatred for adepts and carries a gun capable of firing bullets that can suppress their powers. Copen warns Gunvolt that they are not on the same side, and after a brief skirmish, retreats.
After defeating the Sumeragi agents, Gunvolt's apartment is invaded, and Joule is kidnapped by a resurrected Merak. Gunvolt gives chase, destroying Merak for good, and rides a space elevator to a Sumeragi orbiting platform. Along the way, he encounters the resurrected Stratos, Jota, and Viper and fights them all to the death, before finding that Elise herself had a hidden feral and wild third personality; responsible for the resurrection of the agents. This third personality is killed by Copen, and Gunvolt is forced to fight and subdue him. Gunvolt finally encounters the leadership of Sumeragi, a young psychic adept named Nova. He uses Lumen in combat against Gunvolt, before summoning Joule and three Glaives into himself to transform into a monstrous beast. Gunvolt manages to kill Nova and escape with Joule. In the initial ending, Gunvolt runs into Asimov, his father figure and the leader of QUILL, who offers Gunvolt and Joule new places in QUILL, and reveals an ulterior motive: with Sumeragi in shambles, Asimov wishes to use Lumen, along with the Sumeragi satellite, to wipe out the human race as payback for suppression of adepts. Gunvolt refuses his offer, telling Asimov that he is no better than Sumeragi was, and Asimov responds by shooting him through the heart using Copen's gun (implying that he defeated Copen to steal it from him), before turning the gun on Joule and shooting her as well, leaving them both for dead.
However, if Gunvolt is wearing a special pendant Joule made for him, which is made of collectable jewels that are hidden within each stage, this ending will be revealed as a dream and the true ending will occur instead. The true ending sees Gunvolt on the verge of death as in the initial ending, but he is then rescued by Lumen at the last minute. He awakens to find Joule's body, deathly cold and still. Heartbroken, Gunvolt screams in sadness until he hears Lumen's voice, and ultimately realizes that, in an act of love in order to save his life and be with him wherever he goes, Joule forsook her physical form by fusing her mind and personality with Lumen before further fusing herself into Gunvolt's septimal energy, which amplifies Gunvolt's power to its utmost limits. After this revelation, Gunvolt chases down Asimov, running into Carrera along the way. Carrera demands vengeance for his prior defeat, but is killed once and for all by Gunvolt. Continuing onward to the elevator, Gunvolt confronts Asimov, who reveals himself to have the same electrical septimal powers as Gunvolt. With no other choice, Gunvolt fights him to the death. Following this final battle, Asimov warns Gunvolt that he will never be truly free of conflicts in his life, and dies from his wounds. Zeno and Moniqa meet the space elevator as it arrives, only to find Asimov dead and a heartbroken, wounded Gunvolt, who offers no explanation as to what happened before he simply wanders away into the morning light to be alone with Joule.
Sources and content license
Source and revision history ↗ · Adapted from Wikipedia contributors, Azure Striker Gunvolt. Section headings and formatting adjusted. · Content license