Issei Asamatsu is a third-year student at Fukuhou Technical High School and a member of its boys' volleyball team. His school holds the title of Fukui Prefecture's strongest volleyball team, positioned as the primary rival to Seiin High School after Seiin emerged as a challenger with key additions Kimichika Haijima and Yuni Kuroba. Issei's given name combines the kanji for "one" (壱) and "become" (成), while his surname "Asamatsu" derives from "morning" (朝) and "pine tree" (松).