Upon first seeing Earth from the Azatos Empire's survey ship, Chief Investigator Liza Luna plans to eradicate every lifeform on it immediately, leaving behind only useful resources. While surveying the planet, Liza discovers that human civilization has evolved at a pathetic rate compared to other lifeforms. Liza makes her way to the surface of the planet to properly inspect and understand its inhabitants. Still convinced that there is nothing beneficial to be found, the investigator makes her way into a cafe to gauge the planet's food culture. Liza walks into a cat cafe, where she meets creatures far cuter than anything else in the galaxy. Motivated by this new discovery, Liza decides to investigate Earth's numerous adorable inhabitants.

Fifteen years ago, disaster struck human civilization, and now dangerous man-eating monsters roam the ravaged lands, posing an existential threat to the remaining survivors. Amid this turmoil, an isolated facility shelters children and nurtures them in peace. However, as a few among them find out about the world beyond the narrow periphery of their nursery's walls, their curiosity about it slowly grows. Meanwhile, in the outside world, young survivors Maru and Kiruko band together to search for a special place called Heaven, each for their own reasons. Carrying past burdens and tragic secrets, the two hope to find answers to the cruelty they have experienced in their lives and in the world, which still remains in tatters.

While the funeral of the assassinated Prince Edward, who was the first in line to succeed the throne, is being held, the nobles of the Kingdom of Albion discuss topics such as whether the second-in-line Princess Mary or the third-in-line Duke of Arkham, Prince Richard, will succeed the throne, and how the Duke of Normandy will act. The Duke of Arkham asks Princess if she will side with him or the Duke of Normandy. While wishing to change the world so that all people are equal, Princess is shaken by the Duke of Arkham, who is the mastermind behind Edward's assassination. Meanwhile, Ange and Dorothy are given a mission to infiltrate as Mary's maids and investigate the state of the royal family by the Commonwealth's control. Mary is crushed and exhausted due to the pressure of becoming first in line to the throne. As chaos surrounds the succession to the throne, the Duke of Arkham's plot finally begins to unfold. The darkness writhing in the Kingdom of Albion begins to swallow up Team White Pigeon.

Foolhardy police officer Brian Nightraider is dismissed from the force for a history of reckless behavior that ultimately resulted in his partner's death. While wallowing in self-pity, the disgraced officer receives a curious invitation from the United Nations Immigration Bureau Special Investigation Unit. He has been recruited to join the Marginal Service, a secret underground branch of the UN tasked with handling Borderlanders. Indistinguishable from humans, Borderlanders are aliens that peacefully coexist in society. But now, a Borderlander terrorist organization has emerged, manufacturing and distributing a potent drug called Confu. With the Borderlanders' ability to regenerate and blend in as humans, uncovering the drug-trafficking ring will be no easy undertaking. However, the ra group at the Marginal Service are not one to back down from a challenge—even as their work exposes some unexpected figures as Borderlanders.