• Climate and time of year
• Purpose of travel
• Duration of travel
• Access to laundry facilities
• Aesthetic requirements

Japan will be in the middle of winter; snow is possible in Tokyo and entirely expected at higher latitudes. Since I’m travelling north, warm clothing is the order of the day. Expected temperatures are in the low single digits Celcius in most places, going down to minus-10 depending on time and location.

I’m travelling for self-centred and self-indulgent purposes, so I can carry what I want and leave plenty of room to buy stuff and take it home.

I’m away for the best part of a month but should have frequent access to laundry facilities. Facilities are expected to be serviceable but spartan; I won’t be dry-cleaning any suits or ironing my pants.

Apart from cosplay, I don’t need to dress up or attend any fancy meetings. I can get away with comfortable casual clothes. I might go out with friends a couple of times, so something “smart” would be nice.

For the most part, all of this can be satisfied with very little in the way of clothing. A few sets of shirt+underwear+socks will easily cover the days between laundry. You can get away with a single pair of pants, or two if you really think you need them. A good pair of walking shoes would be a very good investment; I got a pair of Rockports the day before I left and don’t need anything else.

This is very good so far. I can minimise the amount of clothing I pack, meaning I leave more room to carry lots of doujin books home. My secret weapon, then is thermal undergarments.

It’d be easy to bring a big, puffy jacket and a few jumpers, but those would all be bulky and a nuisance to carry around. It becomes particularly inefficient if I have to bring bulky clothing just to deal with the occasions that I’ll be walking around in the snow (as impractical as it is, a snowsuit suitable for climbing Everest would be pretty awesome). Instead, I’ve got an Icebreaker undershirt and a pair of long johns from Mountain Designs (I got the pants from them just to try something different).

They’re both made from Merino wool, so they’ve got a very good warmth-to-weight ratio. It’s also claimed that they’re odour-resistant and highly breathable. They’re significantly more expensive than synthetics, but they should also be much more comfortable, which I think is important for something I’ll be wearing every day. With these, I should be able to get by with a fairly lightweight jacket.

VERDICT: These things are simply fantastic. I’m able to walk around Tokyo wearing a shirt and pants without it being unbearably cold, even in the wee hours of the morning after a night out. I wore them to comiket with a polar fleece jacket when we camped out and everything was good. I wore the same gear up north and to Shirakawa where we were trekking through thigh-high snow and windy snowfalls. As promised, they’re very comfortable and don’t get sweaty during heavy activity.

The Icebreaker is finer compared to the pants and feels a bit nicer on the skin, but the pants are by no means rough. They also say you’re not meant to tumble-dry them but I didn’t have a choice. They shrank a bit, but it just means it hugs my figure a bit more now. Given the chance, I’d go and get the Icebreaker pants for the nicer fabric.