I'm going to Japan this December, so I'll be purchasing one (or two) there. Just wondering, what is on the DVD that comes with some of them? This will help me decide if I should just purchase the ones without the DVD or the ones with the DVD..
Don't forget that DVDs have region codes on them, so they will only play in DVD players that match their region code. Do you have a Region 2 or regionless DVD player? If not, you will be unable to play the DVDs on your DVD player.
Here's the list of countries that are in Region 2 (from Wikipedia
Albania, Andorra, Bahrain, Belarus, Bosnia and Herzegovina, Croatia, Egypt, European Union, Faroe Islands, Georgia, Germany, Greenland, Guernsey, Iceland, India, Iran, Iraq, Isle of Man, Israel, Japan, Jersey, Jordan, Kuwait, Lebanon, Lesotho, Liechtenstein, Macedonia, Moldova, Monaco, Montenegro, Netherlands, Norway, Oman, Qatar, Russian Federation, San Marino, Saudi Arabia, Serbia, Slovakia, South Africa, Swaziland, Sweden, Switzerland, Syria, Turkey, Ukraine, United Arab Emirates, Vatican City State, Yemen
So if you don't live in any of the above countries, native, unmodified DVD players will not be able to play Japanese DVDs.