"Sk8 the Infinity" is a sports anime centered around the underground world of skateboarding in Okinawa, Japan. The narrative revolves around "S," an illegal, high-stakes skateboarding race held in an abandoned mine. Participants, known as skaters, compete in intense downhill races filled with obstacles, tricks, and rivalries, often pushing the limits of their skills and creativity.

The protagonist, Reki Kyan, is a passionate high school student and skateboard enthusiast who works part-time at a skate shop. Reki’s life takes a dramatic turn when he befriends Langa Hasegawa, a transfer student from Canada with a background in snowboarding. Despite having no prior experience with skateboarding, Langa quickly adapts his snowboarding techniques to the sport, showcasing remarkable talent. The two form a close bond, with Reki mentoring Langa and introducing him to the world of "S."

As Langa becomes more involved in "S," he attracts the attention of Adam, the enigmatic and flamboyant top skater who dominates the races with his unconventional and dangerous style. Adam’s obsession with finding a worthy rival leads to a series of confrontations, particularly with Langa, whom he sees as a potential equal. Meanwhile, Reki struggles with feelings of inadequacy as Langa’s skills rapidly surpass his own, creating tension in their friendship.

The series explores themes of camaraderie, self-discovery, and the pursuit of passion through its diverse cast of characters. Alongside Reki and Langa, the supporting characters include Miya, a prodigious young skater with a sharp tongue; Shadow, a flamboyant and aggressive competitor with a flair for theatrics; and Cherry and Joe, veteran skaters with a long-standing rivalry. Each character brings their unique personality and skating style to the races, contributing to the vibrant and competitive atmosphere of "S."

The plot builds toward a climactic showdown between Langa and Adam, culminating in a race that tests both their physical abilities and emotional resolve. Throughout the series, the narrative balances high-energy skateboarding action with moments of character development, highlighting the personal struggles and growth of the main cast. The story concludes with a resolution that emphasizes the importance of friendship, perseverance, and the joy of skateboarding, leaving room for potential future developments in the world of "S."