Originally from a big city, Futaba Ooki spends most days cataloguing her life through pictures on her phone. Upon moving to a seaside town, she gazes out over the vast expanse of sea and quickly becomes captivated by its endless possibilities. Unbeknownst to Futaba, her quiet contemplation catches the attention of local diving enthusiast Hikari Kohinata. Finding herself in the same class as Futaba the next day, Hikari is drawn to her quiet and shy demeanor and affectionately nicknames her Teko, sparking a tender friendship.

Struggling to adapt to the change of pace in her life, Futaba finds herself strung along by Hikari's vast energy and passion for diving. Together, they join the school diving club, led by their homeroom teacher Mato Katori. With Hikari by her side, Futaba works to earn her diving certification while experiencing new friendships and possibilities.