Can dual citizen join JP or US army?

So this is assuming that I'm a dual citizen (of Japan and America of course) and can speak, read, and write in both English and Japanese fluently. My first question is "Will I be about to join the US army without my Japanese citizenship being put into jepardy?" From what I have read/heard, the US doesn't really care if your a dual citizenship in the US army as long as your not an officer. I don't know what the Japanese government will think of this though. My second question is "Will I be able to get into the Kaijou jieitai (Japanese Self-Defense Force)?" I know that the US wouldn't care but I'm not so sure if the Japanese will letme get in because of my Dual Citizenship Status.

Yes, dual citizens can join the US military. Even foreigners can join. The only problem is that you won't be eligible for a security clearance if you're not willing to renounce your Japanese citizenship. Most of the jobs require a security clearance.

I don't know about the JSDF but I assume they have similar rules.

Japan does not recognize dual citizenship. Once they are 21 years old children who were born with one japanese parent must renounce one citizenship. If you are caucasian you would not be taken seriously by the japanese JSDF.

The US Military lets even non citizens join, so I don't see a problem if you are a dual national.

As for the JSDF, technically if you join at age 18 you might since Japan allows dual nationality until 21, any case, it is best to ask a JSDF representative this question to get a full better answer.

As suggested, technically you should have the right to join JSDF. And if they have a problem, tell them that even James B. Harris aka Hideo Hirayanagi, the reknowned radio English teacher whose father was British and mother Japanese, was forced to join the Nippon Teikoku Rikugun during WW2, where he was taught patiently the basics that other soldiers had already learned at high school and was trained by sergeants who'd try to pull out the fighting spirit out of him by shouting "Stab that straw figure thinking he's your British daddy!" Btw, there's more to JSDF than "kaijo," of course.

http://www.amazon.co.jp/exec/obidos/ASIN/4010710519/