High☆Speed!: Free! Starting Days delves into the early experiences of the Iwatobi Swim Club members, exploring their journey alongside fellow swimmers and rivals. As Haruka Nanase and Makoto Tachibana enter middle school, they must navigate the challenges of growing up. While Makoto easily adapts to his new environment and remains enthusiastic about swimming, Haruka finds it difficult to connect with others or join the school's swim club due to lingering doubts from his past experiences. Struggling to choose an alternative club, he distances himself from his energetic classmates. Similarly, Makoto and their peers are uncertain about which clubs to join. However, a disagreement ultimately pushes them toward the swimming club, where they work to refine their skills, synchronize their techniques, and confront their conflicting emotions about swimming and friendship. As they face these challenges, Haruka, Makoto, and their classmates embark on a journey of self-discovery, growth, and determination during their formative years.