Yusuke's own hair is a sort of indigo-black, but clearly what's growing out of McBurn's scalp isn't like anything he's seen back home, at least not without careful application of some pretty bright dyes.

"Truly? The world you come from must be a wonderful sight if people born there look as you do."

No, he's really not flirting, just completely and absolutely caught up in aesthetic bliss. He doesn't even think, his lack of social skills getting the better of him as he steps closer and reaches out to touch one of McBurn's candy-colored locks.