So, I saw a post on another forum a year ago of someone looking for this manga. It's been long since I've lost that post but now I want to find it too. Please note that I didn't read it, I am simply using the information I remember.

So, the story was about a young male slave, probably around 13 years old. He was very smart, and at some point he was bought/rescued by a noble girl, probably around his age as well. I don't know much about what happens after, but there is a relevant part where they both solve a complex enigma/riddle. I'm sorry, for that's all I know

Also, I tried to search for tags/genres, and I didn't get a hit. If anyone could help, I'd be very happy.

Dorei Tensei: Sono Dorei, Saikyou no Moto Ouji ni Tsuki is the only thing that comes to mind, gunna need more info really...