Regarding effects on bone density, miso has an alkalizing effect and the soy can act like estrogen in the body. According to one article, miso also has a variety of bone-building minerals, including calcium, magnesium, manganese and selenium, as well as Vitamin K, which helps the body absorb calcium.
A second bone-building tip for the week comes from my experience with a walking program through my workplace where we try to log between 6,000 and 10,000 steps a day on our pedometers. At the end of the day, when I'm just short about 500 or 600 steps, i go down to our finished basement where the CD player is and play two 4-minute workout songs. It's so much fun to dance to the music that I can get a good 8-minute workout, log all the necessary steps, and make it a bone-building routine by hopping and jumping a bit with the dancing. Sometimes all we have time for is a very short burst of exercise in a day, but it adds up.