Baka Dakedo Chinchin Shaburu no dake wa Jouzu na Chii-chan♡

Both hentai have cute, romantic stories between kind characters, both contain a romance between a nerdy boy and a beautiful girl, and both have lots of sexy vanilla scenes. 

Both revolve around a loser protagonist who become involved with gyarus. Baka Dakedo is just better in every single regard in terms of progression and plot, and the fact that the female protagonist is dark-skinned. However, after you complete the masterpiece that is Baka Dakedo, you should then watch Hajimete no Gal for more gyarus.