Means white cross from German, the series consist in 4 assassins "Aya, Yoji, Ken, and Omi", which one has an unique way of fighting, Aya - katana, Yoji - strings, ken - metal claws, omi - projectiles, they belong to the group Weiß (white) commanded by an mysterious person called "persia" which send them into missions "drug rings, terrorist factions, and the like". As the story roles they find somehow that the ones they fought are connected to an important and prominent clan, the takatori family. They will fight against it to put and end once and for all to this notorious Japanese clan.