((Here's a little more information, only one person has asked about it so far, so I haven't put it up here yet.
The plot of "One Last Chance" is a continuation of something I was thinking about a couple months ago. The Zasshuken were created by humans, so the original zasshuken had no parents (which is mostly every character in the current timeline), but younger characters might have been born naturally to two different zasshuken parents- in that case, usually the stronger gene will win out (much like how it works in humans for various physical traits). They were originally created in secret by the American military to take over the world, and it worked. Then China got leaded the information on how to create Zasshuken, and the world exploded into war. But once the two countries reached a peace treaty, the Zasshuken were no longer needed, and became feared for their abilities. Subsequently, they were hunted down and almost driven to extinction, until the disease came. Which leads us to our current plot.))