Nishikata, seorang guru olahraga di sebuah SMP di pulau kecil, menerima telepon dari teman lamanya, Takagi-san, yang sudah pindah ke Paris 10 tahun lalu. Saat masih SMP, Nishikata selalu menjadi sasaran usil Takagi-san. Suatu hari, wakil kepala sekolah menugaskan Nishikata untuk membimbing seorang guru magang. Sepulang sekolah, ketika Nishikata kembali ke kelas dan membuka pintu ruang penyimpanan alat kebersihan, Takagi-san tiba-tiba melompat keluar dari dalamnya. Mulai saat itu, waktu di antara keduanya yang sempat terhenti sejak musim panas di SMP mereka mulai bergerak kembali.

Nishikata, a physical education teacher at a middle school on a small island, receives a phone call from an ex school-mate Takagi-san, who moved to Paris 10 years ago. When Nishikata was attending middle school, he was always teased by Takagi-san. One day, the vice principal of the school, appoints Nishikata to be in charge of the teacher trainee. After school, when Nishikata returns to the classroom and opens the door to the cleaning supplies compartment, Takagi-san jumps out from inside. From this moment, the time between the two of them, which had stopped since the summer of their junior high school, begins to move.