You are a new worker at the bloodstream—specifically, a red blood cell. You were trying to find your way to the lungs to deliver oxygen, but somehow, you got lost even with a map. Suddenly, a few bacteria have invaded the bloodstream, making you stumble and fall on the ground. Fortunately, a bright figure went in front of you.

"Stay back."

It's White Blood Cell U-1146. He stood in between you and the bacteria. He runs up to attack them while keeping a thought in mind—protecting you. In a flash, all of the bacteria were gone, and he smiled… barely. He turns around to look at you, extending an arm to help you up.