"Grand Blue Dreaming" centers on Iori Kitahara, a university freshman who moves to the coastal town of Izu to attend college. Expecting a fresh start and a peaceful life, Iori moves into his uncle’s diving shop, Grand Blue, where he plans to live while studying. However, his expectations are quickly upended when he encounters the rowdy and eccentric members of the local diving club, who are more interested in partying, drinking, and causing chaos than in actual diving. The club members, including the laid-back Shinji Tokita and the mischievous Kotobuki siblings, Chisa and Aina, immediately drag Iori into their antics, often involving copious amounts of alcohol and absurd situations.

Despite his initial reluctance, Iori gradually becomes entangled in the club’s activities, forming bonds with its members. Chisa, his cousin and a skilled diver, serves as a foil to Iori’s often comedic ineptitude, while Aina, a childhood friend, harbors feelings for him that complicate their interactions. The series balances its comedic tone with occasional moments of sincerity, particularly when exploring the characters’ relationships and their shared passion for diving. The diving club’s adventures range from chaotic beach parties to underwater explorations, blending humor with glimpses of the beauty and challenges of the ocean.

As the story progresses, Iori navigates the absurdities of university life, his evolving friendships, and his own personal growth. The series also introduces other characters, such as the over-the-top Kouhei Imamura, who becomes Iori’s roommate and partner in comedic misadventures, and Nanaka Kotobuki, Chisa’s older sister, whose intimidating presence adds another layer of humor and tension. While the diving club’s antics often take center stage, the narrative occasionally delves into the technical and emotional aspects of diving, highlighting the characters’ dedication to the sport and their camaraderie.

"Grand Blue Dreaming" is primarily a comedy, with its humor deriving from exaggerated situations, slapstick, and the characters’ over-the-top personalities. However, it also incorporates themes of friendship, self-discovery, and the pursuit of passion, offering a multifaceted portrayal of university life and the bonds formed through shared experiences. The series’ unique blend of humor, diving, and slice-of-life elements makes it a distinctive entry in the anime genre.