To put it simply, Children of the Sea is a supernatural mystery. There are marine biological events going on that might possibly be supernatural, and are certainly mysterious. But such a literal description doesn't begin to do justice to this work, where the element of mystery moves in clever and subtle ways. In fact, based on the first couple of chapters alone, it would be easy to dismiss this as one of those rambling slice-of-life indulgences—and nothing could be further from the truth. As it turns out, there's much more to be discovered beneath the surface.

The story begins innocuously enough: ordinary schoolgirl, extracurricular summer activities, a little bit of strolling around the seashore perhaps. This gentle mood draws in the reader effortlessly—if anything, it's the manga equivalent of a soothing summer vacation. But even in these early, idyllic chapters, the stage is already being set for Ruka's grand adventure: her first encounter with Umi comes in dramatic fashion as he jumps into Tokyo Bay, while another critical moment is heralded by the arrival of a shooting star. By alternately contrasting the mundane and the wondrous, this story maintains a strong grip on the imagination, especially in the way it willfully blends the borders between real and fantastic. (Can human children really be raised by dugongs? Well, if you suspend your disbelief just long enough...)

The introduction of more characters and the deepening of mysteries in the second half make the story even more irresistible, adding new layers of depth at each turn. Even the supporting cast has a fascinating charm—Sora, the sickly wandering child; Jim, the old-time surfer who takes care of Umi and Sora; and the sea creatures who also play a key role. Most importantly, the events of the story become ever more adventurous: Umi and Sora take Riku out into open water, where they witness yet another barely-believable event, while back at the aquarium, bizarre-looking deep sea fish start washing ashore. So exact is the sense of pacing that every single scene seems to flow naturally into the next; there's nothing that stands out as a plot hiccup or a forced moment.

At the same time, however, this effortless flow occasionally defeats itself—the events of 300-odd pages could probably have been told in 192 if there had been a bit more editing of all those landscape scenes, or moments of Ruka and Umi just walking around, or the conversational snippets that are only peripheral to the plot. But that seems like a silly nit to pick when the languid pace is the whole point of the story's unique feel.

The other contributing factor to Children of the Sea's uniqueness—and much more immediate in its impact—is the rich, organic artwork. Although it takes a few chapters to really get into the story, there's no such time lag with the visuals, which are outstanding right from Page 1. Daisuke Igarashi doesn't always draw perfectly straight lines, his sketchy cross-hatching occasionally wanders outside the borders, and his character designs aren't exactly marketable or cosplayable—but few other artists can wring so much expressiveness out of pen and ink. The views of the seashore alternate between majesty and intimacy, while the underwater scenes often reach a surreal quality. Of course, that surrealism is enhanced by the exotic species of fish that show up throughout the book (and yes, this guy can draw those accurately as well). Lastly, the widely-spaced panels and fluid character poses give each page an effortless, easygoing feel; this is clearly the kind of story that needs room to breathe.

As a tale that hews close to realism even when unreal events occur, there's plenty of casual, matter-of-fact dialogue to be found here. Ruka's snippy conversations with her father take on the familiar tenor of teenage awkwardness, and her encounters with Umi and Sora usually lead to laid-back (if occasionally cryptic) chatter. Even text-dump moments, like the discussion of disappearing fish at the aquarium and some eyewitness accounts of seagoing babies, are presented in a readable manner—the words are never allowed to overrun the imagery. Since the dialogue sticks to conversational simplicity, a one-page glossary in the back covers all the points of Japanese that need to be understood in this volume. Collectors will also appreciate the color pages, cover flaps and 300+ page count that make this edition worth the price tag.

It has been said that the deep ocean is the true "final frontier"—and no story makes that notion come alive quite like Children of the Sea. Although this introductory volume occasionally drags its feet, it's hard not to get caught up in the flow, as mysteries and curiosities begin to gather like a rising tide. Daisuke Igarashi's penwork shows no weaknesses in rendering the wonders of the ocean, and his understated storytelling guides the plot forward seamlessly. The story of Ruka's summer may have begun in a humble way, but as each layer of plot is revealed, it turns out that this saga has something far grander in store.