Manabi Straight! follows a group of young high‑school girls at the all‑female Seioh Private High School in 2035. In a world where the birth rate has collapsed, schools are shutting down due to a severe shortage of students and teachers, and morale is low, Seioh is no exception. The story begins when Manami Amamiya transfers to Seioh. After a series of early hijinks, including a futuristic scooter adventure and a swim meet, and an inspirational school song performance, she is elected student‑council president. From there, the plot centers on Manami working with Mika Inamori, the only other student‑council member, as they tackle the challenges of leading their school.