Mujitsu and Tairaku's Shakuhachi BBQ

Not having enough breath left to finish is generally either a control or capacity problem. Riley Lee has a DVD called "Breath" that has some very good exercises for both. When it seems like it's taking too long for a breath usually it is that it's taking too long to reset your embouchure after taking a breath and not the duration of the breath that is the problem. Tone exercises with an emphasis on attack might help. You could try also try taking the breath through your nose, that way it's easy to leave your embouchure as it was while you take the breath. I'm not sure if that's an accepted technique for traditional Japanese music though. Or, the if problem really is that the breath is taking too long and it's not a problem with resetting the embouchure, it could be that you're constricting your throat too much. Try keeping your throat relaxed, as if you were going to yawn, but instead of a slow yawning inhale just let your lungs fill up quickly. Try it without the flute, you shouldn't hear much throat noise during the inhale and your lungs should fill very quickly and easily. 

It's very difficult to take a very quick breath after you've been straining to find the last drop of air to get to where you decided you want to breath. Not all breaths need to be equal, you might be able find places to take a few short, quick breaths from a partially empty lung during a the phrase. I wouldn't expect anyone to be able to play for a solid 30 seconds and then go on for another 30 seconds from a quick breath. I'm sure you could find some challenging pieces that require that, and probably some individuals who have mastered that, but there's a fine line between what's realistic and what is simply challenging and that line will change with your progress in learning. I've found that struggling with breathing when it's something above my abilities is wasted time. It doesn't seem to be the kind of problem that extra practice will help with like a particular fingering sequence or how deep you can get your meri's.

rmunk wrote:

I usually practice for an hour and try to do so everyday.  I have been told that when you take a breath in while playing to let your lower stomach pop out with the breath.  But I'm also keeping tension in my stomach while playing and then to suddenly relax and pop the stomach out is a problem.

There really shouldn't be that much tension in your abdominals when your playing, at least not like the kind when people suck in their stomachs for good posture. What it ends up feeling like when you blow is that you're pushing up with your diaphragm, the abdominals get invloved a little but it's still fairly relaxed, and then when you take the breath you just let diaphragm drop. This does make it look like your stomach is popping out
but it doesn't feel like it, at least not like you're pushing your stomach out, it kind of does it by itself. A lot of teachers try to get students to see what it feels like by having them lie down have the student  feel their how thier stomach rises and falls with in and out breaths, feeling both by resting a hand on the stomach and by remembering how it feels internally. This is the kind of relaxed feeling you're striving for while standing and  playing. Trying to grab quick breaths by forcing it is difficult, when your diaphragm falls by itself it's very natural. If you're not working with a teacher because you can't find a local shakuhachi teacher, most silver flute or voice teachers should be able to help and are easy to find locally.

Yes, just sitting relaxed I can pop it out and draw in some air, but when playing it is difficult.