To me, Ibitsu starts out as a love story of two broken souls ... and then the author fucks it all up. But first things first.
If you have read Sundome by the same author (and liked it), you'll most likely also read Ibitsu at some point and will find a lot of parallels or similarities.
The art is quite enjoyable. Apart from Kakeguchi (male lead), who is drawn in a comically simplified and distorted manner most of the time, this manga goes for a simple, but somewhat realistic style. While most of the faces consist of a few simple lines (strokes? whatever) when shown from a certain distance, there is exceptional attention to detail in closeups -- especially when it comes to Madoka's (female lead) body. There is so much detail and it's frickin realistic ... man, I wish they'd make hentai like that (not the wobbly giant tits bullshit and/or genitalia drawn by people who apparently don't know much about human physiology), but I digress. Anyway, art-wise this one looks pretty much like Sundome.
As for the story, well, that's another thing.
Both leads are brought together by some train groping incident. Madoka is groped by an unknown person in the train and Kakeguchi is (falsely?!*) accused.
* The way it is shown, you don't get to see who actually did it, but it looks pretty much as if it was someone else and Kakeguchi was just close when the train suddenly brakes ... and Madoka mistakenly catches him as perpetrator. Also, he is introduced as being way too feared of (real life) women and by no means bold enough to just try to finger bang a girl on the train. I'm not sure I remember everything right, but at some later time -- I think -- it is suggested that he might have been the one after all. That seemed inconsistent and left me a little confused. Figure it out yourself.
However, as Madoka -- through another ... erm ... incident -- gets an idea that Kakeguchi might be just as broken as her (or: kind of complementary to her), she takes an interest in him and forces herself into his home and life. And there starts our strong-female-lead-weak-male-lead super erotic love comedy. Now, if this was anything like Sundome, you'd expect some really heavy blows to the gut and heavy foreshadowing of tragic things to come -- you'll get both. There will be bonerising sex play (doesn't matter if you're not into the stuff that is shown -- it's still frickin hot!). There will be a villain, there will be ... other stuff. There will be danger. There will be laughter. There will be tragedy.
Yada yada yada
However, as both leads come closer to each other, you'll find yourself hoping that everything works out in the end. And it really could. The story would allow for a happy ending (after encountering quite a few obstacles).
After some heavily foreshadowed tragic climax, where the only school friend of Madoka -- who is/was in sexual relationship with the teacher that harasses and abuses Madoka (punch) -- turns batshit crazy out of jealousy (punch punch punch) and splashes acid into Madoka's face (at this point you were expecting something like that ... worse maybe), there is a clean way out of all this mess: Said friend and the teacher are taken into custody or something like that (the point is: the danger is averted). And everything COULD end in a nice way.
But here the author goes for another route: Time jump. Kakeguchi turned crazy, too, caring for a doll modelled after Madoka as if it was her (he's been a ... doll-guy all this time and made that doll when Madoka and him lived together). Madoka accidentally hears of some crazy doll-guy and knows it is him. She attempts to find him. So, for the sake of an even heavier punch, it is made very clear that whatever was between the two leads has become love and that they long for each other more than they could bear. On her way to find Kakeguchi, Madoka gets killed by some former class"mate"-turned-tramp. That's it. Fuck you very much!
While in Sundome the tragic ending had at least some meaning and led to a bitter sweet epiloque, here it seems pointless ... as if the author just wanted to fuck their audience, hard and not in a nice way.