The first part of episode 3 of Free! specials features Rei the night before he started at Iwatobi swim club. Nagisa comes over to lend him a swimsuit and tries to get him to wear a string speedo. Nagisa is such a perve! XD
Rei declines making up the excuse that white is not his color and so Nagisa suggests they call Haruka and Makoto.
Makoto tells Rei he has a sexy body and beautiful legs. And so Rei's swimsuit decision, which we know from the main anime series, was the yellow speedo. The special gives us some more sexy shots of Rei. :D
Yes, it's perfect!
And yes, I'm looking!
There's a few other segments of this special but I'll leave those for you to discover and enjoy!