It all started when a womanizing hero, smitten with his childhood friend Miria, tried to kill Jun, the protagonist, by pushing him off a cliff. Betrayed by Miria due to the hero's lies, Jun loses his will to live, but the Great Sage Sharmane helps him regain it. Awakened by his near-death experience, Jun decides to use the job 'Efficiency Enthusiast' to reach the top. This job awards points for consecutively defeating monsters, which can be used to acquire skills. Jun grows stronger using this efficient method. While Jun doesn't initially seek revenge on the hero, he desires the strength to protect himself from future injustices. He becomes an adventurer in a dungeon city, rapidly rising in rank and making companions. Witnessing Jun's ability to annihilate monsters, people start calling him 'The Thunder Sage'. This story follows Jun's rise to fame as 'The Thunder Sage'. Although he doesn't plan on revenge, the hero seeks him out, leading to a confrontation. Jun easily defeats the hero, causing the hero's downfall. The story also explores the future of Jun and his childhood friend Miria, who were separated by the hero's lies.