Starless: 21st Century Nymphomaniacs

Same art style, drawn beautifully by the same artist and author. Both are great H anime. 

Both start with many girls in a mansion and end with the protagonist as slave 

For some reason, i think Starless is ripped G-Taste stroy from First & Last episode Take example the opening scene from first episode G-Taste & Starless : A female(male in Starless) applicants come to strange mansion inside deep forest for easy job with big payment. After enter the mansion, i leave the rest with your imagination. TL;DR >>> I Recommend you to watch both anime if you like hentai genre with maid as MC 

Manipulative women that gets what they want for their own benefit. Both are great H anime. 

Same producers. That means, they have the same art and animation. Both are great H anime. 

Same art style, drawn beautifully by the same artist and author. Both are great H anime.