Lying on the ground is something that looks just like the ground, the number One. Why is this One lying down? It's been shot by the number two. It's lying there, bleeding out and dying. The number One doesn't have long to live.
As you're sitting there next to One, holding him up, you start feeling a weird sensation all over your skin. From the wound comes a fine powder (obviously coming from the special bullet used to kill One) that causes the person it touches to get extremely itchy (いち).