Three hundred years ago, a genetic experiment gone wrong caused the mutation of all forests on Earth. Armed with consciousness, the vegetation sought to destroy all of humankind, and the war that ensued turned the planet into a hellish dystopia. In the present day, Agito, a young boy, lives with his father in Neutral City—a village maintaining an uneasy truce with the neighboring forest. One day, Agito, on his way to collect water, becomes separated from his friend and stumbles upon a relic of the past: a girl sleeping in a mysterious machine. Agito awakens the girl, Toola Cm Sacl, and introduces her to the village. But outside forces have ulterior motives for the girl, who holds the key to restore the Earth. Misguided by Shunack, a soldier from the old world hellbent on destroying the forest, Toola follows him despite Agito's warning. Determined to save Toola and unify humankind with the forest, Agito borrows the power of the forest and pursues her.

In the fight between the Dragons of Heaven and the Dragons of Earth, the dream seer Princess Hinoto predicts the end of humanity. A central entity, 15-year-old Kamui Shirou, is to choose whether to ally with the Dragons of Earth and destroy civilization to protect the planet or with the Dragons of Heaven to save mankind. Following his mother's last wish, Kamui returns to Tokyo after six years of self-imposed exile. There, he attempts to steal the Sacred Sword from the temple protected by Kyougo Monou—the father of his childhood friends, Fuuma and Kotori. However, after Kamui's venture fails, a mysterious person manages to obtain the sword instead. Believing Kamui to be the man in her prophecy, Hinoto sends the Dragons of Heaven after him to rally him to their cause. Although Kamui first rejects his destiny, the incessant attacks by the Dragons of Earth against those he holds dear push him to decide whether the lives of his friends should prevail over the fate of the Earth and finally pick a side.

Shuurei Kou, the daughter of a noble yet impoverished family, is a clever young lady who dreams of becoming a government official and contributing toward her country. However, her dream is out of her reach as such a position is forbidden to women. While her father works a low wage job as an archivist at the palace, Shuurei has to juggle odd jobs to make ends meet. Then, one day, an unexpected visit changes her life. Shuurei is called to assist Ryuuki Shi, the new emperor who is known for slacking on his duties and preferring the company of men. Tempted by the generous compensation, she readily accepts the chance to become the young emperor's consort for six months. Luckily, she is not alone as Seiran Shi, her trusty friend, joins her as Ryuuki's bodyguard. While tasked with transforming the new emperor into a responsible ruler, court life and politics prove troublesome as Shuurei faces the challenges of her new life. Set in a fictional country, Saiunkoku Monogatari centers on the idea of meaningful leadership, its adversities and the rewards that come alongside a prospering nation.

For over a century and a half, two interstellar states have wrested for control of the Milky Way. The Galactic Empire, an absolute monarchy ruled by Kaiser Friedrich IV and an entrenched nobility, seeks to suppress the rebels daring to oppose the inviolable crown. The Free Planets Alliance, a representative democracy led by a corrupt High Council, degenerates as its elected leaders⁠ use war and conflict as a way to win popular support. But this long-standing stalemate between the Empire and the Alliance ends with the rise of two opposing military geniuses. Reinhard von Lohengramm, a minor noble and High Admiral of the Empire through his strategic brilliance and his sister's position as the favored concubine of the Kaiser, dreams of conquering the galaxy and uniting mankind under his iron fist. Meanwhile, Yang Wen-li of the Alliance, an avid historian and reluctant commodore hailed as the Hero of El Facil, uses his tactical prowess to navigate around his leaders' incompetence—and to carve the path to lasting peace. As the war rages on, Reinhard and Yang each strive for their ideals and to secure their place among the stars as the leaders of a new era of galactic heroes.