A light jacket will suffice. Which part of Japan you will be visiting?

Temperature will going around 14 - 20 Celsius..during that period. Tokyo little bit cold compare Osaka and Kyoto...highly recommended to buy light jacket at Uniqlo ..range budget around ￥4０００　or 　￥ ５０００

http://www.uniqlo.com/jp/

Winter Jacket also available at Uniqlo...during winter ,i prefer light jacket ..much more easy to use..If you take public transport like bus or trains..also have central heating..little bit warm..

This good news for those planning to travel Japan for Free Wifi..this service available at Tokyo , Osaka ,Kyoto and Sapporo .

http://wi2.co.jp/tjw/english.html

i am still fine with a jacket and layering, end of november 

most important you wear a longjohn..

no no...it is inner clothings...pants and top. it will keep you warm. The way to layering is longjohn + sweater + windbreaker jacket.

Uniqlo got sell too..

It's up to you. there's a reason why there is longjohn. besides, it's worn inside and not outside. if ugly, who can see? If you want to wear heavy winter jackets and walk around also can.....

should be ok la bro
bck in dec , around 10 - 15c i wore just like how u describe
if u cant tahan still can buy there
no worries la

If you do get long johns, go for cotton type and avoid wool. Cos when you go indoors, it'll get warm and wool will cause itchiness.

When it gets cold, a warm hat, scarf and gloves works wonders. There are also one time use heat packs which generate heat when unsealed and exposed to air which you can get at Daiso here.

If the wind doesn't blow, can tahan one....but when the wind blows......brrrrrrrrr. Don't forget, the wind is blowing from Siberia 

I normally get by with layering t-shirt, sweater, winter jacket and wear a scarf, ski cap and gloves. Did this in UK, Russia and US. If really really cannot tahan then I add on a light jacket between the winter jacket and sweater.

What kind of temperatures and wind are you expecting?

The winter jacket right, go for those can tahan wind type. Some bergaya tak berguna. When wind blow straight shivering.

Ahh not too bad then. Personally I would use something similar to http://www.uniqlo.com/us/product/men-down-.../down/jackets/~. T-shirt and sweater underneath. Only once in a while I need to add a light jacket to the mix since I have low tolerance to cold.

My colleague survived Geneva in Dec wearing the ultra light down though he said it was a bit cold at times.

Macam boleh but not sure. I always test it on first before I decide. Also you might want to get something slightly longer if you can since you're not wearing long johns. Keep in mind you will be layering so don't get too fitting size.

Here's one of the tips i can give you,

get a rubber type fleece and a good outer winter jacket, big size people body tends to be warmer so what you need is to make sure the heat stay inside not circulating to outside.

12c-20c nothing la hahaha, just like staying in full blown 16c aircond with occasional hyper wind