Fujio Hanaoka, Seiji Kirihara, Shinya Oochi, Masaya Oochi, Madoka Ishii, and Arata Maekawa are close friends who grew up together. While celebrating Seiji's birthday, the group unearths their ten-year-old time capsule, and create a new one, containing penned letters to their future selves, for ten years on. Unbeknownst to the group, they would experience a life-altering tragedy that would not only alter their reality but force them to reassess the verity of their time capsule messages.