Thread:112.211.231.214/@comment-7428000-20200519202432/@comment-7428000-20200520125421

My train of thought was that 1) since Touma only wears the jacket during his fight to stop the level 6 shift attempt on Mikoto and 2) the jacket comes in handy to cover Mikoto after the experiment is over, the appearance of the jacket might be an example of Chekhov's gun (though I didn't state that in the trivia to avoid spoilers of the following manga chapters).

By that train of thought, putting his jacket on after the Scavenger hunt is a reasonable explanation, but not the reason why he decided to put it on :D