[Summary] In A.D 20XX-- Suddenly the Earth had changed into [Half-Infinity Horizon Ground World], which makes the Atmosphere and ground infinitely. [The Silent Walker],the humongous monster who walks forever with no destination, people live on its back instead of the ground of earth, but the mysterious creature named [BO-EN(Greedy Abyss)] came out and it extended their territory. And then the time go past 999 years, now the mankind is in edge of extinction. The survivors made an organization to fight with BO-ENs, and they created new type of battle suits. Now the battle to save the mankind is beginning…