"Viral Hit" centers around Hobin Yoo, a high school student who is frequently bullied and struggles with self-confidence. His life takes a dramatic turn when he stumbles upon a mysterious YouTube channel called "How to Fight." The channel features tutorials on street fighting techniques, and Hobin decides to apply these lessons to defend himself against his tormentors. As he begins to win fights, he gains notoriety and starts uploading his own videos, documenting his journey from a victim to a skilled fighter.

The series explores the rise of Hobin's online persona and the consequences of his newfound fame. As his channel grows, he attracts both supporters and adversaries, including other fighters who challenge him to prove their own skills. The narrative delves into the dynamics of online culture, the impact of social media on personal identity, and the blurred lines between real-life and virtual personas. Hobin's journey is marked by intense physical confrontations, strategic thinking, and the gradual development of his fighting abilities.

Key characters include Hobin's close friend, Taehoon Seong, who provides moral support and occasionally assists in fights, and Jinho Lee, a formidable opponent who becomes a recurring rival. The series also introduces a diverse cast of fighters, each with unique motivations and backgrounds, contributing to the complexity of Hobin's challenges. Themes of perseverance, self-improvement, and the ethical implications of using violence as a means of empowerment are woven throughout the story.

As Hobin's popularity soars, he faces escalating threats, both online and offline, forcing him to confront the darker side of his viral success. The narrative maintains a balance between action-packed fight sequences and character-driven moments, highlighting Hobin's growth as he navigates the pressures of his dual life as a high school student and an internet sensation. The series ultimately examines the transformative power of self-belief and the consequences of seeking validation through public recognition.