Levi's Unknown Fight...?!

is an extra chapter included in the second volume of the Attack on Titan: No Regrets manga, written by Gun Snark and illustrated by Hikaru Suruga.

Summary
In a tavern in the Underground, the tavern keeper beats a patron at a match of arm wrestling. The proprietor gloats before his amazed onlookers, proclaiming that he is undefeated. Noticing the "underground hoods" in the corner, he challenges them to a match. He claims that if they can beat him, he will offer them both a free meal and his own wife. His wife objects to this, and Levi accepts the challenge while Furlan and Isabel watch. Isabel cheers while Furlan asks that they do not take the "old lady". As soon as the proprietor starts the match, Levi slams his arm against the barrel, winning the match in a split second. Levi approaches the man's wife as the proprietor begs him not to take his wife. Reaching behind the man's wife, Levi takes a canister of tea leaves, departing from the tavern with Furlan and Isabel.