The story begins when a lecherous hero, who had a crush on the protagonist's childhood friend, Miria, tried to kill the protagonist, Jun, by pushing him off a cliff. Jun, who had lost the will to live after being betrayed by his childhood friend due to the hero's lies, regains his strength with the persuasion of the Great Sage, Sharmaine. Awakened by the attempt on his life, Jun decides to aim for the top using the job class 'Efficiency Chef (Affisentator)', which allows him to gain points by defeating monsters in succession. Using these points to acquire skills, Jun gradually grows stronger. While he harbors thoughts of revenge against the hero, he focuses more on strengthening himself to never be harmed unjustly again. Jun becomes an adventurer in a dungeon city, rapidly rising in rank and making friends. Witnessing Jun's ability to decimate monsters in a stampede, people begin to call him the 'Sage of Thunder.' This is the story of Jun's remarkable achievements that earn him the title 'Sage of Thunder.' Although he did not plan to seek revenge, the hero comes to him, leading to the hero's downfall. The story also explores the relationship between Jun and his childhood friend, Miria, who were separated by the hero's lies.