If you're looking for manga similar to Otona no Manaa, you might like these titles. All recommendations are made by Anime-Planet users like you!
Keitatsu x Ran from the prequel Wild Boyfriend are back again and are inseparably lovey-dovey and hot in love! Soft spoken megane danshi by day and fierce erotica by night. Featuring some hot springs erotic contact and lots of steamy naked bodies. Just like love conquers all; can wild sex conquer all?!