True Love Story Summer Days, and yet...

After his mother dies, Yuuta Morisaki and his older sister Ruri move to the city. In a school hallway, Yuuta bumps into Hina Kusunose, a cute but slightly clumsy member of the tennis club. Hina remembers the past they share. Little by little, Yuuta begins to recall the childhood promise he made to the girl he used to play with back when his mother was still alive.