It is not often that you'd come across an ecchi harem manga, where the main characters aren't afraid to follow-trough and express their affections for one another, just like any real couple in an actual relationship. Yet that is exactly the kind of manga you've stumbled across. Umi no Misaki being an Ecchi, Harem, Slice of Life, with a greater focus on the Romance to enhance its relaxing story; revolving around an island community, with its own ancient customs and cultural traditions.
Set in the radiant & lush island of Okitsu; a city boy named Nagi Goto travels to such an isolated rural environment, for both family reasons and to visit the "Ocean's Cape" his late mother talked about. It is there he meets a local girl, who he then becomes acquainted with, subsequent to a near-death incident. This is what kicks off a chain of events, whereby he eventually learns of the customs within Okitsu, which involves their traditions surrounding the island deity known as the "Dragon God". And Nagi eventually becomes a major part of it all.
This is what basically occurs during the 1st volume and the volumes that follow just further develop the story, in a slow yet more romantic sense. Now I must say that the romance that occurs in Umi no Misaki is quite remarkable for a harem and will keep a lot of readers hooked, even without much comedy or drama, which a lot of harems can't seem to do without. Even with its sluggish pacing and how it constantly skirts around the major issues, the mangaka seems afraid to address, the well done & tasteful romance is what makes this manga worth reading. Because beyond that, there isn't much to this harem's drawn out story.
Now for this to be recognized as a harem, a male protagonist is usually required and it comes in the form of our young adolescent/young adult (it's never really clear) Nagi Goto. In the beginning there’s not much to him or his personality, as Nagi feels just like one of those blank slates in the beginning of an average visual novel. However he quickly becomes very involved in the plot and to an extent, a rather charismatic character to both the readers and the girls.
The girls in question are not quite the one-dimensional, cardboard cut-outs, with labels like "dandere" & "tsundere" plastered on them. No instead of relying on such generic archetypes, they almost resemble actual girls (almost) that have been born and raised in a closed-off community and it's rather refreshing that it often shows things from their perspectives. The 3 main girls (Shizuku, Karin & Soyogi) all have contrasting personalities and it’s remarkable to see the effect Nagi has on each of them, over time. However it stumbles across the usual pitfalls of having interesting main characters and side characters that range from dull to plain annoying.
Yet one area this manga doesn't falter is in its incredible artwork, with a style that mixes realistic environments and stylistic characters. The scenery is beautifully drawn, with fine detail put into the building architecture, ocean waves and even the foliage. Whereas the characters are much more simple-looking yet well-drawn, with excellent facial expressions. Though their features can sometimes be out of proportion and the blushing cheeks tend look out of place and overdone, but I guess I'm just nitpicking here.
Overall Umi no Misaki is a harem manga I'll remember, not for its fanservice or generic scenarios filled with misunderstandings. But for the way it handled the romance, making it feel like a "true harem". Whereby the characters genuinely feel like they are in a relationship with one another and not just fumbling into each other. The whole island and its cultural traditions, isn't a unique concept in the story, but it is handled in quite the unique fashion and helps spice things up gives the romantic story some direction. Unfortunately the story lacks some much needed tension and even though it tries to shoehorn some towards the end, it comes across as rather sloppy and leads to a rather anti-climactic finish. Yet even with the way things drag on to a point that it could kill ones interest, I'll still recommend Umi no Misaki to anyone who enjoys a good romance or harem.