At the climax of the Eve Wars, on December 24 of the year AC 195, the armies of the World Nation and White Fang met in a ferocious battle. World Nation leader Treize Khushrenada was slain, White Fang leader Zechs Merquise disappeared, and Earth was saved from destruction by the intervention of the five Gundam pilots. Having witnessed the consequences of war and hatred, the people of Earth and the space colonies put aside their differences and together founded a new world government. Under this newly-formed Earth Sphere Unified Nation, a year has passed in peace. The government and the populace have disarmed themselves, and almost every remaining mobile suit has been destroyed. Deciding to follow suit, Gundam pilots Heero Yuy, Duo Maxwell, Trowa Barton, and Quatre Raberba Winner place their mighty mobile suits inside an asteroid and send them on a one-way voyage into the sun. But even as they bid their Gundams farewell, a new conflict is drawing near. 

(Source: AniDB)

A large scale catastrophe is occurring across the planet. Ability users are discovered after the appearance of a mysterious fog, apparently having committed suicide, so the Armed Detective Agency sets out to investigate these mysterious deaths. The case seems to involve an unknown ability user referred to as "Collector," a man who could be the mastermind behind the incident.

Trust and courage are put to the test in order to save the city of Yokohama and ability users across the world from the grip of Collector where the Armed Detective Agency forms an unlikely partnership with the dangerous Port Mafia. 

[Written by MAL Rewrite]

High school student Haru Yoshioka is bored with the monotony of life. One day, she saves Prince Lune of the Cat Kingdom from being run over by a truck. As a token of gratitude, the Cat King sends her "presents" and invites her to the Cat Kingdom to become Lune's wife. Haru's inability to properly communicate with the cats leads to the misunderstanding that she has accepted the proposal.

As Haru ponders on ways to escape the predicament, a mysterious voice instructs her to search for the Cat Bureau. However, not long after she finally arrives at the bureau, a horde of cats swarms in and forcibly takes her to the Cat Kingdom, along with a member of the Cat Bureau. Concerned for their safety, owner of the Cat Bureau, Baron Humbert von Gikkingen, follows close behind.

The more Haru immerses herself in the activities of the Cat Kingdom, the more cat-like she becomes. To her dismay, she soon learns that, unless she can find her true self, she may become a cat permanently. Haru's adventures in the world of cats lead her down a path to self-discovery, allowing her to return as a more confident person.