幼児退行してくる第七王女の執事になったんだけど

The Seventh Princess, Luciana, calls out, “Babuu! Carry me!”  

Rondo, a young man who was reincarnated into another world, suddenly finds himself sold off as a male prostitute. It is at this grim moment that he realizes he is a reincarnator. In this seemingly hopeless situation, Rondo gets his first customer—the Seventh Princess, Luciana, who comes to him for some “babying.”  

After various twists and turns, Rondo is purchased by Luciana and becomes her exclusive butler. From that day onward, he serves her faithfully.  

Now with a bit more freedom, Rondo begins to use his knowledge from the game world to strengthen himself, gradually becoming unstoppable.