Kitahara Iori moves back to the seaside town of Izu where he grew up in order to attend university. He’ll be living with his uncle, who runs the Grand Blue Diving Shop. Upon entering, Iori is met with a scene he never thought he’d see: a huge group of naked burly guys playing rock-paper-scissors.
Iori flees the site, but is quickly caught by two of the dudes, and learns they’re juniors at Izu University, making them his senpais. They were playing a game to determine who would fill their scuba tanks; they’re in a diving club and want to recruit Iori, who declines as he can’t swim.
Iori won’t just be living with his uncle, but his two female cousins as well, Nanaka and Chisa, both of whom have grown quite beautiful in the ten years since he’s seen them. There’s a particular aura around Chisa that suggests she’s looking forward to seeing Iori, or at the very least will give him a chance.
Iori blows that chance without even realizing he had one, because just as he walked in to a debaucherous display, so too does she, with him at its center, half-naked, drinking, shouting, and generally acting a damn fool (i.e., a college freshman). His attempt to smooth things over fails specatularly; Chisa’s first impression of him is that anything he touches must be thrown away.
His senpais Shinji and Ryuu demand he party with them that night, assuring him they’ll get him to orientation on-time. They do, but with two caveats: he’s hungover six ways from Sunday, and he’s in nothing but his boxers. That is how the whole of his freshman class meets him.
Iori has been swept up in the waves of college life, and it feels like his seniors are giving him a “swimming” lesson of sorts. The only way to learn is to jump in and start paddling, but Iori’s attempts to do so only invite more scorn, not just from Chisa, but from a hot blonde guy named Imamura Kouhei, who wears a t-shirt declaring his otaku-ism.
He also gets plenty of attention from the cops for continuing to ask people for their clothes. He finally gets a shirt by recruiting Kouhei to the Diving Club, which is called “Peek-a-Boo.”
Iori is inevitably thrown into more situations of cavorting and heavy drinking, and both he and Kouhei prove ill-equipped to resist the temptation to overdo things. To be fair, the peer pressure to drink as much strong liquor as possible is extremely high…though we see that Chisa is able to sip responsibly and stay above the fray.
The morning after their latest college party experience (involving a staring contest in which one person tries to get the other to spray their drink) both Iori and Kouhei arrive at class in their underwear. Clearly more swimming lessons will be needed…but despite Iori’s insistence the Diving Club is not for him….c’maaahn. You know that cat’s joining.
Grand Blue looks great and is a lot of fun, effectively capturing the raw energy and abandon of early adulthood. Those who have attended college know that it isn’t just about studies, but the experience; the change in one’s lifestyle to something more independent than one’s home. It’s about making a new home, and making a new family.
Most importantly, it’s about trying new things (and yes, sometimes failing and/or suffering). But as Yoda said in The Last Jedi: “The greatest teacher, failure is.”