@Cralkx: I was thinking something along those same lines. His face isn't very masculine, neither is his build, and his behavior is decidedly effeminate. As an example of the latter, think back to his conversation with Kuroda in the previous chapter: that strained outburst of emotion, one that has her bending over as if throwing the words at him and squeezing her eyes shut while speaking to him? That's the sort of thing he's done since the very first chapter--you might consider that his character-defining moment, if you're used to seeing that in various other anime/manga.
If he acts so much like an overly emotional woman, he might as well dress like one, too.