It is common knowledge that nobles will do anything for power; lying, manipulation, and extortion are the usual tactics. However, one family is exempt from this generalization: House Grail, whose main tenets are truth and integrity. The youngest daughter, Constance Grail, is just as moral as the rest of her family, believing in always doing the right thing and helping those in need. However, these ideals do not help her when her fiancé cheats on her with another woman. Framed by his lover in the hope of her downfall, Constance has no one to hear her pleas for justice. Everyone turns a blind eye, save for one—the spirit of the infamous Scarlett Castiel—who possesses Constance and turns the tables on her accuser. However, this aid does not come without a price. Ten years ago, Scarlett was executed for the attempted murder of Princess Cecilia. But this was actually a setup; as blunt and harsh as Scarlett could be, she would never stoop so low as to use poison. She has no idea who orchestrated her incrimination, but Scarlett demands that Constance—as the only one who can see her—help her exact revenge on all those who wronged her!

Saku Chitose appears to lead an enviable high school life. Extraordinarily charismatic, tremendously confident, and effortlessly friendly, he is the kind of person others naturally look up to. But his popularity carries its own burdens; not everyone views him kindly, and whispers of cynicism follow wherever he shines too brightly. To Saku, living an ugly life is worse than death—a belief that drives his need to maintain his perfect reputation. At the start of his second year, Saku's homeroom teacher asks him to help bring back a classmate who has stopped attending school. Initially hoping to resolve the matter quickly, Saku finds out that the shut-in Kenta Yamazaki harbors open contempt for him and everything he represents. A simple favor instead exposes the distance between those who live within the social light and those who were never given a chance to shine. Surrounded by the expectant gazes of those who both admire and despise him, Saku treads the delicate line between sincerity and performance—searching for what it truly means to live beautifully in a world that sees only the surface.

Enticed by its rumored wealth, Cid Kagenou happily tags along with his sister, Claire, on a trip to the infamous Lawless City. The region is ruled by three monarchs: Yukime, the Spirit Fox; Juggernaut, the Tyrant; and Elisabeth, a dormant progenitor vampire known as the Blood Queen. Hunting Elisabeth down serves as the perfect opportunity for Claire to prove her true mettle. On the other hand, Cid has different objectives—sneaking away from Claire's sight, collecting as much loot as possible, and making Shadow's glorious entrance at the perfect moment. As Elisabeth's awakening draws near, her subordinate Crimson enacts a treacherous plot, sending the town into a frenzy. Searching for her now-missing brother, Claire finds an unexpected ally in Mary, a vampire hunter, and the pair hurry to the Crimson Tower—the home of the Blood Queen. Meanwhile, Beta and a small team of Shadow Garden recruits also arrive at the Lawless City. As the key players converge on the Crimson Tower, the stage is set for a grand confrontation under the crimson moon.

After the decline of the once robust fields of science and technology, a new energy source known as magic fuels the modern era. Humanity creates forbidden biological weapons: Gears. Those Gears eventually stand against humanity in a rebellion. Although they manage to overcome in the struggle for survival known as the Crusades, humanity's losses are so great that even after several decades pass, their emotional wounds remain unable to fully heal. Sin Kiske, the child of a human and a Gear, heads to his father Ky and mother Dizzy's wedding ceremony. Their wedding breaks the ultimate taboo: a union between a human and a Gear. Even with the world at peace, it took many years for such a ceremony to come to fruition. Despite the complex array of emotions surrounding it, the wedding ceremony is met with blessings. When suddenly, a mysterious girl appears... The fated child inheriting Gear blood–and the mysterious girl who despises Gears. Their meeting would shake the world. (Source: Official site)