If you're looking for anime similar to Green Green Thirteen: Erolutions, you might like these titles. All recommendations are made by Anime-Planet users like you!
Shouta is a 25-year-old NEET. At his class reunion, he is mocked by all his former female classmates who've all become successful. A time-shift at the school pool throws him back in time to his 5th grade years and gives him a second chance to deal with those same classmates when they were fifth grade girls. Now he faces a dilemma: he may change his destiny or he may stay as the same loser.
Both series contain a lot of inappropriate ecchi which is generally considered to be in bad taste. The series both have major perverted characters in there and even contain a tinge of the supernatural or very light fantasy.
Main difference between these two is that the main focus on the shows is in different spots. Mujaki no Rakuen is more focused on the perverted and uncomfortable main character and the complete naivety of the girl characters, while Green Green is more of a harem-y romcom. Also, Green Green Erolutions is far more explicit.