Japan once had a legendary surgeon known simply as K. His speed, precision, and overall brilliance were unmatched, and he assisted a countless number of patients. However, five years ago, he vanished, never to be heard from again. Now, a man who looks identical to the original K has appeared, claiming to be a descendant of a long line of shadow doctors who have worked behind the scenes. This new K is just as talented as the original and has chosen to continue the work left by the old K. He has vowed, as a doctor, to uphold the importance of human life.