Hailing from a large city, Futaba Ooki spends the majority of her days documenting her life through photos on her phone. After relocating to a coastal town, she looks out over the wide sea and is swiftly captivated by its boundless potential. Unaware of this, Futaba's quiet reflection draws the notice of Hikari Kohinata, a local diving enthusiast. The following day, Hikari finds herself in the same class as Futaba; attracted to Futaba's reserved and shy nature, Hikari affectionately dubs her Teko, initiating a gentle friendship. Having trouble adjusting to the slower pace of her new life, Futaba finds herself swept up by Hikari's abundant energy and enthusiasm for diving. They join the school's diving club together, which is run by their homeroom teacher, Mato Katori. With Hikari at her side, Futaba strives to obtain her diving certification while encountering new friendships and opportunities.