In the far future, the elevated irradiation from the sun has destroyed the environment of the earth and the birthrate of humans has drastically decreased. The government controls society with an army of cloned soldiers called "Ideal Children (IC)". Sam Coyne is a trader in a desert. One day, he saves a beautiful woman Maya, who has been chased by Theseus, a corps of IC. He shelters her in his trade ship, but the destroyers of Theseus surround Sam and Maya.

Part II of Sword Gai: The Animation.

When the gods would not answer in humanity's desperate hour of need, it turned to a demon instead. The supposed savior came wielding the sword Zsoltgewinn, but its uncontrollable lust for blood led it to kill those who summoned it too. Although the sword was sealed away long ago, it has been uncovered by the Shoshidai, an organization that collects such cursed artifacts. However, Zsoltgewinn proves to be too strong to be tamed by humans when its corruptive power influences the administrator, Takuma Miura, to flee with it in his grasp. At the same time, Gai Ogata's family is torn apart due to the possession of another demonic sword, Shiryu, leading his father to be murdered and his mother to hang herself shortly after giving birth to him. Abandoned in the forest clutching the blade, he is discovered by the blacksmith Amon. Unnaturally transfixed by the sword, Gai works tirelessly for years to hone his smithing skills. However, when an accident costs him his arm, he gains a new one—in the form of a reforged Shiryu. Now having a cursed sword for an arm, Gai must learn to control its violent urges. All the while, Zsoltgewinn continues its rampage, leaving a path of blood in its wake.

In the year 2032, the legendary idol unit "7th Sisters" suddenly retired from the industry and disappeared. That was the end of the idol industry... until two years later, when a young glory-seeking employee is appointed to be the leader of Tokyo's next generation idol studio, "777 (Three Seven)," commonly referred to as Nanastar. However, the city continues to believe that idols are a thing of the past, and Nanastar is no exception. Their slump continues, but one day a mysterious and beautiful female manager approaches you and says, "If the idols of the past are gone, we'll just have to make new idols! True "sisters" linked by powerful bonds!" The story of the idols of the future, the Nanastar Sisters, will now unfold. (Source: Tokyo 7th Sisters Wiki)