The number 1 trip for traveling is this: If you are checking any luggage you are doing it wrong, period.
There is almost no reason, with rare exception of actually carrying some sort of large item (guitar, surf board, some sort of business product for a presentation, etc) that you should have anything besides carry on luggage.
You are traveling to a developed country. Everything that exists for you to survive in that country is already there as noted by the 126 million people who already live in said country comfortably. You could literally hop on a plane to Japan tomorrow with nothing more than a passport and your wallet and you would be 100% fine. In fact you could do the same for almost much any country, developed or not. People over pack out of fear of the unknown when in reality if the "unknown" occurs the 20 extra dress shirts they packed in their checked luggage isn't the thing that is going to save them.
Advantages:
1. Freedom. You've got everything in one bag that is with you at all times.
2. Security. No lost luggage because you aren't handing it over to anyone else.
3. The less crap your bring the less crap you have to worry about forgetting.
4. Speed. You are in and out of the airport, cab, train, bus, etc while everyone else is held up by their luggage.
This is backed up by the thousands of business travelers that know what they are doing who fly around the world multiple times a year with one carry on plus the experienced world travelers who live out of a single carry on bag for months on end. In fact I moved to Japan 1 year ago with a carry on only and had no other luggage shipped over. I even managed to pack my newly purchased desk top (broken down and without the case of course), laptop and my huge full sized headphones with me in my carry on bag. This is addition to the other travel I've done, including previous trips to Japan, Taiwan, and around the U.S. with carry on only.
Tips:
1. You can wash clothes on a vacation, contrary to popular belief haha. You either buy some detergent when you get to Japan or bring a small bag of powder detergent with you in your bag. Every evening when you get in the shower you simply wash any clothes you got dirty for that day and then hang them out to dry. By the next morning most things will be dried out and ready to go again, and that's if you want to wear the exact same stuff two days in a row haha.
2. Learn how to pack correctly.
http://www.onebag.com/pack.html