@dndragonsHe was thinking back to what he got. But he's watching to new trainees.
Also, many characters in the anime can be seen wearing items that aren't part of the uniform. I.e. Mikasa's scarf, That scout guy who had the do rag, random people in the background occasionally have one.
Not to mention that said mask is also in his CS which was accepted.
ALSO, sorry if my post wasn't clear about the fact Ryuu is watching new guys. I'll edit it later to make it more clear! My bad!