Basically, a guy with no name who attends college is obsessed with sex -- mainly, sex with women. He bumps into a preppy girl on the way home and winds up inside her apartment, when -- what else? -- sexy times commences. Only it's more kinky sexy times than anything else. And did I mention his snazzy pick up line? Throwing a jar full of semen at her. Nice. Between that and the ending which is all kinds of messed up, it warrants a 6/10. Story brings nothing original to the table, but it's not completely devoid of ideas.
Art is possibly the worst
thing when it comes to Zero no Mono -- and for a hentai anime, poor art is a killer. The character designs are boring, the girls' bodies look rather the same with the exception that part of preppy girl's body has bandages on it. The guy looks like a filler-drawn version of Rex from Yu-Gi-Oh!, which detracts from any fapping experience you could have with this piece. Not to mention during some of the sex scenes, it becomes blindingly obvious the animators got lazy and just looped small parts of animation to make it look like they did more work that they did. Art gets a 4/10 -- at least they kept it consistently mediocre, right?
Sound is pretty good. The voices for the characters, especially the main male's VA, sound rather fitting for their roles. The standard moans & groans during sexy times are all right, nothing special. Background music is classic hentai soundtrack, complete with wailing sax and low-key piano. 7/10 is the sound, making it probably the highlight of the anime, technical-wise.
Everyone is rather cookie-cutter in terms of characters: there's the bored sex fiend, the preppy girl looking for kinky sex, the nonunderstanding teacher, the nameless couple having sex in a deserted area. Even the supposed plot twist of the true nature behind the preppy girl isn't very shocking seeing as she had acted that way since her first scene, but meh. At the very end, the main character seems to have a temporary change of heart -- is living only for sex a way to live? -- but savor it while you can, for it leaves as soon as it arrives. 5/10 for character.
I enjoyed myself watching this as much as anyone would, I suppose, except I couldn't stop thinking things like "how can he stick his hand up that far without breaking something?" -- in other words, there wasn't a proper suspension of belief to truly enjoy this anime. Not to say I hated it, it just seemed like I took more pauses than usual due to the plodding nature of the piece's pacing. 6/10 for enjoyment.
Overall: It's a short OVA piece that isn't a total waste of space but has too many detractions to make it a quality piece of hentai -- namely, the animation and the characters. But the techniques executed during the sex scenes, not to mention the Jar O' Semen and the twist at the end, might be enough to warrant a watch purely for the lulz. In overall, I'd give it a 5/10, and suggest it only to those bored and looking for a truly mindless hentai or just oddly curious at the basic idea behind Zero no Mono.
Also, throwing your own semen at a random girl on the street = worse way to pick up chicks ever.