In ancient China, during the Warring States period, a former servant named Xin rises through the ranks with a dream: to become the greatest general under the heavens. Fighting alongside King Ying Zheng of Qin—who seeks to unify China and end the chaos—Xin leads his own unit, the Fei Xin Force, onto the battlefield. With power reclaimed from the influential Chancellor Buwei Lü, King Ying Zheng begins laying the groundwork for a new, unified legal state with the support of key allies like strategist Changping Jun and legalist Li Si. As Qin launches a campaign to seize new territory from the state of Zhao, their advance is halted by the brilliant strategist, Li Mu. In response, Changping Jun devises a bold plan: to bypass Zhao's defenses and strike at the key city of Gyou, near Zhao's capital. To carry out this risky maneuver, a powerful coalition army is formed—led by the tacticians Ou Sen (Wang Jian), Kan Ki (Huan Yi), and the warrior queen Yo Tan Wa (Yang Duanhe). Joining them are the next generation of Qin commanders: Xin's Fei Xin Force, Mou Ten (Meng Tian)'s Gaku Ka Unit, and Ou Hon (Wang Ben)'s Gyoku Hou Unit, each operating independently. The fierce battle for Gyou begins, as the future of Qin's unification hangs in the balance. (Source: MAL News)

The moments Keisuke Niijima shared with his wife, Takae, were the happiest in his life. After their first meeting as coworkers, the bond between them gradually became stronger. They eventually married and were blessed with a daughter named Mai soon after. However, following Takae's death, time seems to have stopped for Keisuke, resulting in his inability to build a proper relationship with his daughter. Ten years later, the gloomy Niijima household is bound for change when a little girl knocks at the door—claiming to be Takae's reincarnation. After confirming her identity, Keisuke's world brightens once more as he revels at the thought of making new memories with his beloved family. Unfortunately, this fortuitous miracle comes with its obvious drawbacks, and one mistake will spell more tragic consequences for Keisuke and everyone else involved.

Akane Nishimura's quiet nature makes her classmates perceive her as a gloomy and unlikeable person. Combined with her intimidating gaze, it earns Akane the ominous nickname Grim Reaper, condemning her to endless bullying for her supposed cursed powers that bring misfortune to everyone around her. However, none of these rumors deter transfer student Taiyou Takada from trying to befriend Akane. As someone who finds the supernatural fascinating, Taiyou approaches the Grim Reaper without hesitation, blissfully unaware of the complicated situation within the class. His bright personality and optimistic worldview may just bring about the change that Akane desperately needs.

Following the conclusion of the large-scale coalition campaign, the entirety of China is in a state of economic recovery. The victor of the battle, the state of Qin, is no different. There, the political parties led by Ying Zheng and Buwei Lü continue their inner conflict. Having played the role of king in the coalition battle, Zheng has the trust of the people—but Lü is far from out of the fight. In 18 months, he plans to interrupt Zheng's coming-of-age ceremony. Meanwhile, a Zhao army numbering 20,000 troops has set out toward Qin. In the royal court, due to the lack of generals capable of responding to the incoming threat, Lü slyly suggests that Zheng take command. However, Cheng Jiao, Zheng's half-brother, volunteers instead. As they grew to trust each other during the coalition battle, Zheng now accepts Jiao as his replacement. However, the Zhao forces retreat a mere half-day after clashing with Jiao's army. With trouble quickly brewing in the shadows, the internal struggle of Qin is only complicated further. There are only two men Zheng feels he can rely on: Bi, a general who commands 30,000 men; and Xin, the leader of the Fei Xin force.