Story: All you need to know about plot is that this guy has a heart condition and... etc etc etc... chugs down a banriku- Banrink- a drink that gradually turns his heart into a macguffin for ultimate power among oni. And he's protected by two hot oni chicks. Sorry, 10,000,000 yen and an extra year of life for his heart to be eaten at the end of that year. His delicious heart needs to mature and all. That's pretty much it for the spiffy premise.
What then progresses is combat, fanservice, a bit more combat, more fanservice, mammaries, some truly dispicable content and more fanservice. You really aren't here for much more than that, excluding said dispicable content. The contents in the middle are pretty good, it develops on things, makes the characters grow a bit and then throws it all away. It begins to crumble near the end, with chapters that deviate from what matters, chapters devoted to fanservice (Obligatory fanservice and the mandated quota of areas/sites), a few short chapters and while I don't entirely mind the second one, it just feels like filler with a bit of character development now and then in those segments. Usually it would just return to status quo without developing anything.
Plot threads are left hanging, sub-plots are left to whither, no sense of time and the ending, gives me a feeling that it was cancelled. Only spoiling possible disappointment but, you know... you know what to expect. Nothing tour-de-force but it had potential and some really great moments. If it had more time, it could have been so much more.
Art: Aww yeah, mammaries and fanservice. You got the cows, the lolis, the Chesty LaRue, the boobs and all the good stuff. Some flaunt them, some show skin, skin is shown throughout and it's good ol' family fun. Otherwise, yeah, I liked it. It's manga like these where I can neglect everything but things related to fanservice and solely judge art on that. But to it's credit, there are some neat designs and some of the magic that's used is truly awesome.
Characters: I guess... I can say I didn't hate most of them. I disliked a few, some of the kids, but I actually liked them. There's a bit o' development for some of the secondaries as well as the mains and for it being what it is, a titty fighting manga about hot oni and a female:male ratio of 7:1, it's good. Although some hardly get any development and are there for kicks, it's still better than it has any right to be.
Overall: It had potential, loads of it, but it was squandered and it became rushed, which only added to the fault of not having any feeling of time in-manga. It's trash, certainly, but it still has it's thrills and action, fanservice and some truly good moments. But what would you expect from a cover where half of it is mammaries?