Before I begin, something important to note about this franchise are the characters being an incestual family. While that might seem obvious at first, what is more important to note is that it has multiple generations. The MC of Imouto Paradise 1 is Souichirou Nanase. Souichirou has sex with all of his sisters as seen in the hentai, but they all come to have kids. Those kids are the second generation where Keichii Nanase is the MC along with all of his half-sisters which are the daughters of Souichirou. Then Keichii has sex with all of his half-sisters which leads to the third generation where Yuuichi Nanase is the MC with all of his half-sisters being the daughters of Keichii.
It's integrated incest. ( ͡° ͜ʖ ͡°)
Imouto Paradise! 2 is based on the second eroge of the franchise: Imouto Paradise! 2 ~Onii-chan to Go nin no Imouto no Motto! Ecchi Shimakuri na Mainichi~ Yet in terms of anime, it follows a completely different animation and artstyle. In fact every single work in this franchise uses different artwork and animation. There is absolutely no consistency in this franchise, so don't dive into this expecting that.
As aforementioned, the main focus of this iteration is making the characters feel immaculate. While the art style does not take any special liberties on that front, the animation makes sure to introduce many reaction scenes to breathe more life into the sex scenes. That said though, the art does far outstrip the artwork in Imouto Paradise! 1.
Imouto Paradise! 1 can be summarized as a completele mismatch of style. It's like putting spaghetti on ice cream. Just cause the powerfucking style that Murakami Teruaki is known for in hentai like Taimanin Asagi has good dynamics, doesn't justify the painfully pastel color pallete and woozy camerawork that tries to get you to ignore god awful scenes like the egg-yolk licking scene. The Imouto Paradise eroge is a vanilla icecream hentai. Why the hell are you trying to put a hamburger patty in it with Imouto Paradise 1?
Imouto Paradise! 3 takes a nosedive in animation quality and has subpar art. The only thing the third iteration has is its linework, which is a shame because linework does little to making characters sexy. It reaches a level where even the animations in the Eroge, Imouto Paradise! 3 ~Onii-chan to Go nin no Imouto no Sugoku! Ecchi Shimakuri na Mainichi~, supercede the animations in the actual hentai. It also drops the reaction scenes which makes the hentai feel a lot more rigid with little to negative improvement to the quality of the art.
Imouto Paradise! 2 may have limited it's characters to only 2 out of the 5 half-sisters. However, their absolute dedication to making these two characters as lively as possible makes it leaps and bounds greater than the rest of the franchise. It is the only hentai in this franchise that is actually higher quality than its respective Eroge.
