what to wear to Japan?

My friends and I will be going to Japan from 27april-3may. We'll be arriving in Osaka but will travel to Tokyo and Kyoto during our stay. How is the weather like? What should we wear?We're from Singapore so we don't really know much about what to wear for the different seasons.

The weather in Singapore should be the same as Japan. And, if it's different, go shopping. There is no better souvenir than the one you can wear around and show your friends.

Just a little colder.

Actually I would expect it to be a bit cooler in Japan than Singapore at that time of year- you can get some cool mornings and very strong winds still in May- June. If you go to Nikko it can be 10 degrees colder there than it is in Tokyo on the same day, so bring/ buy some sort of light jacket and a sweater at least.

I believe it should be around 10 to 15 deg in Tokyo right now. While I was there this year late march, I wore one t-shirt and one windbreaker so the body feels warm enough. But it's my face that suffered the most damage as it was not covered from the chilly wind. And due to the dry condition, my lips cracked several times :-(

Windbreaker is recommended. But light jacket will do. Bring small umbrella as it may rain. Some lotion and lip care should be considered to prepare. As you know, things in Japan is not that cheap.
Enjoy your trip.

like shaz, i m also going to japan sometimes in early june. I was wondering what kind of clothing should I bring. Cause of the weather in singapore, we wear a lot of tank top, tube, three quarter pants/jeans etc. is that ok?

Yes, that's fine, but bring a light sweater and/ or a jacket to cover up with as it can still get cool, especially if it's windy. Some buildings and trains can also be over air-conditioned, so people in Tokyo always carry something to cover up with.

If you are going to Nikko, bring something warmer as it can get really chilly there in June, it is at 1000m and was only 13 deg when I was there last July.