It is clear from his expression he is sitting here trying to imagine himself with a tail. Considering the expression on his face and Jiro's, it is no wonder they get compared to their box weapons. Two more adorable puppies may not exist side by side than the two right here.

Then he laughs, shaking his head "That would be kind of cool. Except, it might get in the way of training." Why yes, there is currently an image of himself, with a tail trying to play baseball in his head. There may be tail wagging involved but he's not telling.