After graduating from high school, Kitahara Iori (voiced by Uchida Yuma) successfully entered the university and is about to start a brand new university life. In order to go to school, Kitahara came to a city located on the seaside. The marine climate, which is completely different from that of inland cities, makes Kitahara full of longing and hope for his future life, and also makes him start to get involved in the interesting sport of diving. The lively and cheerful and slightly strong personality of Furukawa Chisa (voiced by Anji Chika), the gentle and considerate Furukawa Naka (voiced by Uchida Maaya) who is actually full of strong possessiveness for her sister Chisa, and the arrogant girl Kitahara Shiori who often contradicts Kitahara but is actually full of interest in her brother. Here, Kitahara quickly met a group of like-minded friends. What kind of meaning will Kitahara, who joined the diving club, find in this sport?