“Huh?! Kyaaaaak!!! W-Why did I suddenly become an anchovy?!!!” He majors in food and nutrition and has a first-class certificate as a daily sports instructor, the epitome of being a fitness enthusiast, Choi Young-jik! Well, that was who he used to be… Waking up in the body of Prince Soo-yang, the second son of King Se-jong the Great, he lost all of his bulging muscles overnight. Young-jik was taken aback when he realized he might be able to meet King Se-jong, his father. He couldn’t contain his excitement at the thought of meeting the magnificent King Se-jong, whether or not it was a dream or reality. H-Huh? King Se-jong… the Great??? There sits in front of him, a chubby man who looks like he’s struggling to breath. King Se-jong the Great appears to be severely obese and possibly diabetic… Government officials had chronic illnesses and frail bodies… Choi Young-jik, a seasoned fitness trainer with 15 years under his belt- holding the pride of the fitness community- begins to feel a fire ignite inside him. “Alright, shall I try spreading the fitness craze in Joseon?!”