Futaba Ooki, originally from a busy city, documents her everyday life through smartphone photos. After relocating to a seaside town, she looks out at the vast ocean and becomes mesmerized by its endless charm. Hikari Kohinata, a local who loves diving, notices Futaba's reflective moment. The next day, finding themselves in the same class, Hikari is intrigued by Futaba's quiet nature and gives her the nickname Teko, gently guiding her toward a growing friendship.
Struggling to adjust to her new, slower-paced life, Futaba slowly gets pulled into Hikari's lively world and enthusiasm for diving. Together, they decide to join their school's diving club, led by their homeroom teacher, Mato Katori. With Hikari's encouragement, Futaba works toward getting her diving certification, discovering fresh friendships and adventures along the way.