[Rin wants to coral everyone together because 1. it's safer and 2. he wants all his nakama to be nakama with each other. Sousuke, seriously, have you not learned the first thing about Rin yet?]

Someone might, but the lockers are too small to fit the mats, and it's not like I can carry them all around the school all the time. Unless we could find somewhere else to hide them...