The study of Japanese black pine is incredibly rewarding. I don't really recommend getting your feet wet with the species by starting seeds, though. Once the seedlings have emerged and begun to grow, at just the right time they are removed from the soil and all the roots are cut off (at just the right point), then dipped in rooting hormone and potted up. This encourages a good nebari. Then certain techniques are applied to encourage growth and development of shape and branching. Starting JBP from seed is actually a quite advanced technique. I recommend starting with slightly more developed trees if you can find them.
Here is an article detailing my own use of one year old JBP pine seedlings from Van's Pine Nursery. I started with 100 frozen plugs and so far, I still have about 25-30 left that are developing well. I expect with the experience I have gained I will have better results next time.
Here is another article that I discovered after I had already begun my experiment. Looks like Brian Gershuny has been carrying on for a little longer.
Good luck to you.