Carry enough inners to avoid having to wash them. It is quite chilly there, and even if you manage to wash something, it will not dry. Carry at least one pair of socks for the day, as they tend to get dirty quickly.
Carry a scarf/muffler, ear muffs, and other accessories.
If you're travelling by train and can't get a seat with air conditioning, bring plenty of blankets. At night, it gets really chilly.
Light woollens, such as a light full sweater, shawl, or jacket, should be carried in the evenings. Otherwise, casual attire such as jeans and T-shirts is OK. However, if you want to go out at nights, you will need to bring a pair of shoes or sneakers with socks.