A heroine summoned to another world as a bonus for being a "saint"—what awaited her was a forced marriage to a bird-man with deadly poison...!? Kanzaki Rui was summoned to another world along with her twin sister. While her sister, who has an aptitude for all kinds of magic, is treated as a "saint," Rui, who has no aptitude for magic and only possesses "poison resistance," is treated terribly. One day, Rui is forced to marry the emperor of a neighboring country overrun with beastmen, as a substitute for her sister. The emperor himself is descended from a demonic bird that harbors deadly poison, and is known as the "Emperor of Poisonous Venom," possessing deadly poison all over his body. A "political marriage" between a lonely king and a substitute saint. The destinies of these two, who should never have intersected, begin to move little by little. (Source: Echo, translated)

King Kushihiko, the younger brother of the king, who was born with a disability affecting one side of his body, receives a gift from the empire at his inauguration as commander of the Royal Guard. It is Arame, a female slave wearing a bear mask. She was a fearsome criminal who led a rebel army in the empire. Unwillingly becoming her guardian, Kushihiko finds himself living a strange life with her, unaware that this encounter marks the beginning of the king's death and a tumultuous conspiracy. In the chaotic, dawning kingdom, the jesters dance. Like a tragedy. Like a comedy. A spectacular court drama revolving around the throne!