Yang Rui, a nerdy, overweight Ph.D. candidate in biology, faces unemployment after graduation. He unexpectedly becomes a versatile, top-tier instructor at a cram school. A twist of fate sends him back to 1982, where he's reincarnated as a tall, handsome high school student preparing for the college entrance exam, his mind brimming with knowledge from his past life. The college entrance exam in the 1980s had a very low acceptance rate? Classmates, learn from me... Job assignments were rigid and formulaic? Come to my place, and I'll tell you how to do it... If the country is in trouble, I'll help my juniors! If someone is sick, I'll help my classmates! This is the story of an impure technician.