Adorably sexy is the best way to describe Oppai Heart. You don't know what the hell is going on half of the time, but it's made damn clear that there are bitches in heat that need to chill.
This hentai suffers from a severe lack of clarity. It's as if they went, "Fuck the story! We all know what you're here for, so let's get on with it." Fortunately, this means the two episodes are chock filled with actual sex rather than melodrama.
Unfortunately, this comes at a severe cost in clarity and even drags down their personality. I keep on saying it, but it is quite evident. The main premise of the show, why they are in heat in the first place, is never even explained. The lack of setup feels jarring. It's as if you are eating a burger without the top bun. It's still a good burger, but how the heck are you gonna hold it without getting your hands dirty?
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All the storyboarding nonsense aside, Oppai Heart truly is adorable. The few moments where the characters aren't banging, there are snippets of the characters developing their love for each other. It relies on vanilla fetishes like the cat nya~ sounds/expressions, naked apron, cheerleader suit, and marriage. All with plump busts of course. There is plenty of things to enjoy about this hentai.
While the main theme is satisfying the two main female horndogs, one episode for each, the sex scenes are great due to the variety of sexy poses. The scenes are largely at the level an above average hentai, but the faces are adorable works of art. Kind of sounds strange pointing it out, but the face designs and expressions seriously are phenomenal. The voices also adds something to adore. Hell even the guy sounds adorable--which is a surprise since he isn't a shota.
As a result, Oppai Heart ends up being your average hentai. Even rating this on hentai scales, this can only be average at best as the lack of clarity creates a strange flow which is quite jarring at first. Fortunately, it's not so bad upon rewatching it, which makes up for the lacking setup. It could be an above average hentai simply due to its artistic sense, but the lacking exposition cuts it down a notch. However, for the consummate need to ravish and breed, this hentai will always have a special place in my heart.