Season 1 · 12 episodes
Futaba Ooki, a shy girl who had just moved from Tokyo to the beachside town of Shizuoka, catches the eye of her eccentric classmate, Hikari Kohinata, who instantly befriends her.
On her way to school, Hikari races against her homeroom teacher, Mato Katori, who she discovers to be a fellow scuba diver. Later that day, Hikari drags Futaba to the school's Diving Club, where they try on some drysuits and take a dip in …
Hikari leads Futaba to a road filled with cherry blossom trees to cheer her up. The next day, Hikari and Futaba sign up for the Diving Club, where Mato, the club's advisor, teaches Futaba about air pressure and ear equalization.
Futaba comes to observe a scuba diving class run by Hikari's grandmother, Kino. The next day, Futaba has her first experience diving in the school's pool, struggling to keep water out of her eye mask and losing confidence. However, with Hi…
Noticing Futaba struggling with strength, Mato has her and Hikari go jogging to build up strength. Along the way, they come across some students from diving school, Ai and Makoto Ninomiya, who turn out to be their upperclassmen in the Divi…
Futaba undergoes a pool course at the indoor pool, managing to properly learn how to clear her mask. However, it soon becomes apparent that Futaba doesn't actually know how to swim. Following the lesson, Mato takes Futaba and Hikari on a d…
On a rainy day, Mato decides to follow Hikari as she boards a train, discovering that her only reason for doing so was to witness some blooming hydrangeas for a brief instant. Later, on a particularly hot day, Mato has the club play red li…
Makoto becomes concerned when Ai receives what appears to be a love letter from her classmate, only to later find it was addressed to another girl. Later, as Futaba and Hikari take part in various fitness exams, Hikari helps Futaba improve…
Futaba, who always takes photos to remember each moment, becomes shocked when her phone's memory has become full, requiring her to delete or move her old photos, including those of her friends from Tokyo. As Futaba finds herself unable to …
Futaba and Hikari invite Ai to hang out with them as they go shopping for logbooks and swimsuits. Afterwards, the girls go to the beach, where Futaba tells Kino about all the things she has learned since meeting Hikari. Futaba expresses he…
Futaba and Hikari follow the club's mascot, Cha, leading them to take a path that neither of them has been down before. Along the way, they come across a small kitten that appears to have been separated from her mother. With neither girl a…
The Open Diver course begins, with Futaba and Hikari paired up as buddies. Futaba loses one of her fins on the way to the descent point, but it gets picked up by another diver, turning her fears of the unknown world beneath her into excite…