"A Toast to the Nape of Your Neck" was originally a one-shot published in 1997 in the back of Maki Murakami's Gravitation vol. 4 tankoban. It became it's own serialized manga in 2001...and never finished.
S T O R Y - The original short was actually a really cute story, and it worked well as a one-shot. Sure, it had potential to be a longer series, but I was always pretty happy with it being what it was -- many things with that sort of quiet potential have been subsequently ruined, after all. Kanpai! expands on the premise of the one-shot and changes a number of things around. The characters' names are changed, and they're (pointlessly) regressed in age from high school to middle school. The protagonist gains an overarching purpose in addition to his quest to win the heart of a classmate -- to protect all monsters, who've become endangered from human overhunting. Nothing spectacular, but good enough, I guess. Unfortunately, Kanpai!'s storytelling is very scattered and jumps around from one thing to another.
Many of the short arcs seem like lengthy gags more than anything else, but even as a comedy, the humor seems rather forced and depends almost entirely on "WTF" reactions. The actual plot, if there is one, is lost in the chaos. Really, if there's a discernible storyline beyond Shintaro chasing Nao around, it's lost to me. Yes, Shintaro's purpose is to protect monsters, but that stated purpose doesn't necessitate plot sadly. Instead, we have two volumes of varied shenanigans and the occasional twist, some of it entertaining, some of it not so much. Kanpai! ends abruptly on a cliffhanger hardly a year into its run; I like to think that Murakami suddenly realized that she didn't have much of a story after all and that "A Toast to the Nape of Your Neck" should have just stayed a one-shot.
C H A R A C T E R S - All of the characters in Kanpai! are exceedingly one-dimensional. Shintaro is spunky and energetic; he is proud of what he does and works hard to succeed. He's also madly infatuated with the nape of Nao's neck with no explanation whatsoever (initially). Shintaro is good-natured and good-hearted, and it eventually becomes clear that he cares plenty about Nao as a person and not just a slab of neck. How amazingly predictable. That sort of cookie-cutter personality might work all right for a one-shot, where little development is expected to begin with, but for a longer work, it gets really boring, really fast. Nao's personality shifts somewhat from her original one-shot counterpart, but the change is not for the better. Nao is very tsundere, and that's all that really needs to be said because she grows or evolves beyond that.
The all new supporting cast is more a handful of vaguely amusing gimmicks than a collection of real characters. Short mini-arcs introduce each one before inducting them into the group of usual suspects, but honestly, they're not very interesting. Kenken is a demon werewolf gone permanently human after Shintaro saves him. Yabe is a ghost that was unceremoniously resurrected. Sakurai is an excorcist with some muddled kind of purpose. Shintaro's father is some kind of mysterious badass, and Ponta is a stereotypical butler/caretaker-type character that freaks out a lot. Yawn. Being a bunch of stereotypical characters isn't the downfall though; the only downfall is that none of them ever change and become anything interesting beyond their one-liner description.
A R T - Kanpai! began serialization near the end of Gravitation's twelve volume run and around when Murakami's artistic maturation and evolution was plateauing. For the most part, the art in Kanpai! is pretty solid, though many things could stand improvement. The rendering of animals is often laughable, and it's not uncommon for characters' hands to be very undersized. The characters are quite consistent and easy to recognize from situation to situation, but the character designs themselves are often too reminiscent of those from Gravitation and therefore incredibly distracting. The similarities get so bad that even TOKYOPOP can't help but comment on it on the back of their volume 2 release: "... and although he's NOT you-know-who from Gravitation, the resemblance is striking indeed!" And by "striking," they mean that the guy introduced at the end of volume 2 looks EXACTLY like Yuki Eiri. Murakami's familiar chibis and outrageous caricatures also appear throughout this series, emphasizing its generally chaotic humor.
O T H E R - TOKYOPOP licensed and published both volumes of Kanpai! for North American release in 2005. The translation feels pretty good and natural, though I get the impression that they only expected people already versed in manga to be interested in the series. All honorifics are left intact with no initial note to explain their meaning. There's also no explanation for the general Japanese usage of surnames until characters are familiar with each other. Romanization of a few names are a bit inconsistent, with "Shintaro" appearing on the backside summary and "Shintarou" appearing everywhere on the inside. "Ponta" is also initially translated with a dash over the "a," but that disappears almost immediately. As with most modern TOKYOPOP translations, the tankoban reads right-to-left, the sound effects are left untranslated and as-is, but small text in signs and books in the background are translated. All in all, a pretty good job, I'd say.
O V E R A L L - Honestly, I never really expected Kanpai! to be much good. I bought the two volumes because they were on sale for $0.99/ea, and I figured hey, the one-shot was cute, so I might as well, right? As disappointing as it was, it was good to see something else of Murakami's other than Gravitation and related doujinshi, and I regret nothing. ...Still, I'm now inclined to think that Gravitation's success was a huge fluke, but I guess they can't all be winners. I don't recommend Kanpai! to the curious passerby-er; there are plenty of other, more interesting, series to waste your time with. Actually, I don't think I'd even recommend Kanpai! to the Gravitation fan -- it might make you question Murakami's actual abilities too much.