When a gate to another world suddenly opens on Earth, Mikado City is invaded by strange creatures known as "Neighbors," malicious beings impervious to traditional weaponry. In response to their arrival, an organization called the Border Defense Agency has been established to combat the Neighbor menace through special weapons called "Triggers." Even though several years have passed after the gate first opened, Neighbors are still a threat and members of Border remain on guard to ensure the safety of the planet. Despite this delicate situation, members-in-training, such as Osamu Mikumo, are not permitted to use their Triggers outside of headquarters. But when the mysterious new student in his class is dragged into a forbidden area by bullies, they are attacked by Neighbors, and Osamu has no choice but to do what he believes is right. Much to his surprise, however, the transfer student Yuuma Kuga makes short work of the aliens, revealing that he is a humanoid Neighbor in disguise. [Written by MAL Rewrite]

Putting his life on the line, Willem Kmetsch leaves his loved ones behind and sets out to battle a mysterious monster, and even though he is victorious, he is rendered frozen in ice. It is during his icy slumber that terrifying creatures known as "Beasts" emerge on the Earth's surface and threaten humanity's existence. Willem awakens 500 years later, only to find himself the sole survivor of his race as mankind is wiped out. Together with the other surviving races, Willem takes refuge on the floating islands in the sky, living in fear of the Beasts below. He lives a life of loneliness and only does odd jobs to get by. One day, he is tasked with being a weapon storehouse caretaker. Thinking nothing of it, Willem accepts, but he soon realizes that these weapons are actually a group of young Leprechauns. Though they bear every resemblance to humans, they have no regard for their own lives, identifying themselves as mere weapons of war. Among them is Chtholly Nota Seniorious, who is more than willing to sacrifice herself if it means defeating the Beasts and ensuring peace. Willem becomes something of a father figure for the young Leprechauns, watching over them fondly and supporting them in any way he can. He, who once fought so bravely on the frontlines, can now only hope that the ones being sent to battle return safely from the monsters that destroyed his kind. [Written by MAL Rewrite]

This anime is based on a playstation game under the same title. The story is about four people who travel the desolated land of Filgaea and carve themselves a legendary story while they're at it. These adventurers are Sheyenne Rainstorm, a gunslinger who holds the legendary weapon called ARMs; Kiel Aromax, a scientist who looks like he should be carrying a sword; Roleta Oratorio the Crest Sorceress, a magic-user who uses cards called Crests to cast spells; and Mirabelle Graceland, one of the Noble Red, which are a family of vampiric creatures who live alongside human beings They also travel with cute little intelligent furry things, from the Popepi Pipepo Tribe, named Isaac and Jerusha. (Source: AniDB)

Masane Amaha and her daughter Rihoko are on the run from a government child welfare agency that wants to take Rihoko away from her mother. They are caught and Rihoko is taken away. Meanwhile, Masane is attacked by an advanced weapon that can disguise itself as a human being. When faced with the danger, a strange light emits from her wrist and she transforms into a powerful being. She destroys the weapon and consequently becomes involved in a power struggle between powerful organizations, with her at the center of their attention. Because she holds the greatest power of them all, the legendary Witchblade. (Source: AniDB)