If you don’t read Japanese, you might not find the link to the maker’s blog, which has pictures of all the different braiding and weaving tools he’s made. I like the cardboard marudai that hangs off of a water bottle.
Robin, if you can scan in the Japanese text or get a good picture with your phone, someone should be able to help you figure out the accessories (my Japanese is rusty, especially kanji, but I’m stubborn!). I think that model comes with parts to use it like an ayatakedai (koma in the front, arms on the back to hang the double wefts over), in addition to the takadai and marudai setups. You might have some koma with different-depth slots, and I think those are for the ayatakedai “feathers”.