Imouto Paradise!

Both of them have cute "imoutos" (Little sister). Both are hentai. If you like one of them, i'm sure you'll like the other one too.  

Both have incest and neither one has hardcore stuff in it. All of it is tame and good. 

Both Zettai Junshu and Imouto Paradise have the same art style and camera work. Thats right, Murakami Teruaki's gone and made another master piece. In Imouto Paradise all the girls are the protagonist's sister, unlike Zettai Junshu where only one girl is a cute little imouto. If you enjoyed the sex scenes from popular hentai anime such as Taimanin Asagi and Dark Love then you're going to love this. 

Same animation style and camera work technique. 

Both are hentai genres and contain pettanko/loli/young girls. Given the light-hearted tones of the atmosphere of the setting, the animation in itself is quite the opposite. Both titles are also random and plot-less, but if you enjoyed one of these, then you will enjoy the other for the heroines.