Energy Kyouka!!

In both H-Anime the main Heroine is a Gal/Gyaru, cheerful, proactive, nymphomaniac, loose woman, JK, and openly makes advances on anyone she likes. This nice stereotypical scenario is served by very good drawings, excellent animation, nice body positions and enjoyable body proportions… Making it the whole thing hotter! 

There's slutty girls in both with also at least one being the gyaru type, besides that both have lovey dovey incest sex between siblings, Energy Kyouka!! Has little sister and Ecchi na Onne-chan is as the title implies big sister, this last one's focus is entirely on the wincest, while Energy Kyouka!! Is more on the slutty side, but both are enjoyable. 

Both OVAs are about slutty teenage girls pleasing old men, well there's also some same age guys in Energy Kyouka!! And J* Fuuzoku Gakuensai is just one guy winning over all the girls at a slut academy, but both have the gyaru type of girls, if you like gyaru, be it completely slutty getting it on with a lot of different guys in a gangbang, or just with one lucky one, I'd say go for it. 

There's not much of similar between the two, besides that both have a character which is the tanned, blonde dyed, skimpy outfits wearing and slutty gyaru, the likeness is obvious from the cover of both alone, there's other girl in both which is in the more young looking side, well also that all the girls involved are joshikosei, that is highschoolers, but that's all. 

So funny thing, the anime of Energy Kyouka!! Didn't kite adapt all the manga, so in the second episode it kinda ends as a harem with the protagonist's big brother, there's some confessions and romance there, which reminds me of Imouto Bitch Ni Shiboraretai, the part of bitch is only present in the title and the body proportions of the imoutos in there, so there's not much going on for the rest of the similar aspects of both, since Kyouka is a complete slut for the whole first episode and partially in the second, but just for that second part vanilla incest this deserves the recommendation. read more 

Both involve slutty highschool girls pleasing another students or old salary men, both with some gyaru love thrown in there too (Energy Kyouka more than the other, definitely), Enkou Shoujo Shows the process of the female becoming a slut, which is actually more creative in execution, but both are great. 

Both include public sex, group sex, and public group sex, the difference being the girl in Energy Kyouka enjoys it from the beginning and the girl in Rinkan hates it at first and starts to enjoy it later.