In Mahotsukai no Yoru, Alice and Aoko mention the “May King” as an enemy they’ve fought before. They mention that because of his superior concealment skills he was able to break past their bounded fields. Is this referring to Robin Hood? That’s the name of one of his skills and part of his noble phantasm, but it doesn’t make sense for them to have ever come in contact with Robin Hood, servant or no. They also mention that they encountered him in Sherwood Forest. Which is where Robin Hood is from.