I will be the first to admit that I am not that fashionable, but I do know how to pack for trips that involve a lot of walking and exploring! I have been to Japan several times over the years and, it seems to me at least, I ALWAYS choose the rainy season for my visits. Here are some lessons I have learned:
Jeans and other heavy cotton apparel will end up damp and in danger of mold. Look for travel pants in lightweight materials that will dry fast or something else light and not wrinkle prone. Knit is good, if you like the look. (I don’t, it clings to my butt….)
Carry an umbrella. A rain parka may well end up just as damp on the inside (from sweat) as on the outside…. That said, I usually travel with a rain parka or waterproof windbreaker just in case. There is the occasional hurricane, making umbrellas pretty pointless.
I always argue in favor of trying to blend in. Wear short sleeve blouses, or t-shirts (preferably with a synthetic content so they dry quickly) instead of spaghetti straps or halter tops that bare your shoulders. Or, anything that exposes your bare tummy. And ALWAYS make sure your shirt isn’t see-through when wet! Shorts are considered sporting goods, if you wear them you will be immediately marked as a tourist unless playing in the water or out hiking. Skirts should be knee length or longer.
In Japan, ALWAYS have nice socks! You have to take off your shoes in too many temples, restaurants and residences. Holes in your toes will be embarrassing. No, you won’t get out of taking your shoes off, no matter what sort of insanity you claim.
On the same subject: In Japan, your shoes should be easy to remove and put back on. Balancing on one foot while tying your shoe makes for a great image but isn’t really practical. I have a pair of light slip-ons for nice wear and a pair of running shoes with the laces replaced with elastic laces for long days of walking. I do take hiking boots if I expect to hike up mountains, but people don’t expect you to slip shoes on and off on mountains….