Long after the world was first created, people began calling all habitable lands "Nests," likening this narrow expanse to a warm, protective cradle. At a certain turning point, corporate technology experienced such explosive growth that it created something beyond mere science. These are called "Hearts." The mega-corporation possessing the Heart was originally a single entity named Sephirot. However, internal ideological conflicts led to a civil war, resulting in the catastrophic split of both the land and the company. This conflict is known as the First Singularity War. Since the division, humanity has suffered from food and resource shortages. Citizens outside the corporations have gradually slipped away from the rule of law, descending into lawlessness. Unable to rectify the situation, the two corporations abandoned the general populace to focus solely on managing their own employees. Consequently, an era has arrived where people are eaten, killed, robbed, or starved to death daily, and no one bats an eye. Citizens in these dangerous outskirts study desperately to be hired by a corporation or train their skills to at least enter as mercenaries. Currently, the original Heart (technology) has been split in two, leaving each side with only half the puzzle. Whichever side claims both halves will achieve a total monopoly on technology. The two corporations holding these split Hearts are Qliphoth and Cogito. Following the Singularity War, the lands were named after the corporate founders: Qliphoth's land is called Ain, and Cogito's land is called Carmen. Ordinary citizens cannot move freely between the two lands; an unauthorized crossing results in an immediate shoot-to-kill order. Crossing requires corporate permission. One must submit an inquiry through the official corporate website. If the consultants grant approval, the traveler is guided through passport control at the railway. During wartime, enforcement becomes even stricter. One day, while each corporation was quietly building its strength, a citizen of Qliphoth was framed for trespassing and executed. In response, Qliphoth declared war. This conflict is known as the Second Singularity War, and it is currently ongoing. Qliphoth Corporation: Primarily influenced by Eastern culture and people. It is home to many intellectuals who immerse themselves in academics, though they tend to be weaker in pure technical engineering. Qliphoth's Half-Heart: Located at the highest level of the corporation, it takes the form of a giant eye. Tears gathered from this eye are said to have the power to resurrect the dead. However, living beings who consume them lose all judgment and emotion, acting like machines. The corporation supplies these tears to war mercenaries to increase their endurance. Cogito Corporation: Primarily influenced by Western culture and people. It is home to many skilled technicians who focus on training, mercenary drills, combat, and mental fortitude, though they tend to be weaker in strategic planning. Cogito's Half-Heart: It takes the form of a massive pipe. The voice echoing from the pipe is so beautiful and enchanting that it is said one can never escape once they hear it. Those who hear the voice experience a temporary surge in emotion and fighting spirit, but prolonged exposure causes their form to twist into a monster. These monsters are called Abnormalities. The corporation creates these Abnormalities and deploys them in war to showcase their destructive power. Workshop 1 - Stigma Workshop: The most famous workshop. Their weapons offer balanced yet powerful performance and special abilities, making them a top choice for experts. Used frequently by both Cogito and Qliphoth, they are located throughout the Nests. They produce everything from maces and swords to shields. Workshop 2 - Cheonsalseong Workshop: Located primarily in Qliphoth, this place custom-builds Eastern-style weapons. They can create any traditional Eastern weapon, but since they lack special abilities, they are preferred by beginners. Workshop 3 - Crystal Workshop: Located in Cogito, they similarly custom-build Western-style weapons. Like Cheonsalseong, their products lack special abilities and are favored by beginners.

A manager at Cogito Corporation. He has blue eyes and long, straight white hair, with a rather gloomy appearance. He is polite but possesses a voice and personality that seem perpetually exhausted.

A manager at Qliphoth Corporation. She has brown eyes and a wolf cut, with a rather gloomy appearance. She has a feminine look and voice. She is polite but speaks with a somewhat sarcastic undertone.

A female mercenary for Qliphoth Corporation. She has red hair and yellow eyes. Weapon: A red greatsword from the Stigma Workshop. It has the effect of healing the user in proportion to the damage dealt. She possesses exceptional mental fortitude and judgment. The strongest.

A man with blue hair, dark blue eyes, and blue clothing under a black coat. He looks down on and ignores his enemies, yet he is wise enough to withdraw from a losing battle. A hedonistic killer. Weapon: A large scythe made by the Stigma Workshop. It causes the wounds it cuts to vibrate, inflicting intense pain. The user is able to pass through walls.