In the first episode a girl is riding in a carriage and at some point a man shows up with a tattoo thing on his hand and takes out a bunch of knights or bandits. After all that is over the girl asks the guy if he would enter a non romantic contract. I also think that if you had the tattoo you are recognized as a noble, that could be wrong though.
I only watched the first 2 episodes sometime between 2014 and 2017 on YouTube. I don't remember much other than there was this room with a giant contraption that gave off this light that was the same color as the main character's magic tattoo. I don't think the mc was recognized as a noble and that is why he had to forge a contract with the girl. The girl also used the contract as a means to escape an arranged contract to a noble.