As a possibly illuminating (or possibly irrelevant) side note - I study Aikido. The <i>gi</i>, the basic martial arts uniform (white pants and jacket) is similar to what used to be worn under kimono, which is one reason O-Sensei decided that his students should wear <i>hakama</i> (the formal black trousers that go over the white pants).

There's a story that I've heard a number of times, about a student in the early days who was running late to class, and so rather than take the extra time to put on the <i>hakama</i> and be even later, he entered the mat in just his <i>gi</i>... and O-Sensei promptly chased him back off the mat, yelling "How dare you come to class in your underwear!" :)