I unfortunately did'nt get to attend, but that is where I train. It was held at the Tsubaki Kannagara Jinjya, in Granite Falls, WA. My Sensei, Reverend Koichi Barrish, a shinto preist, was teaching.
The Seminar was Aiki Taisai, held to commemorate O sensei's B-day. Tsubaki
It might be hard to give a descriptive answer on that. but basically, our style of Aiki is headed by Shinto priests, and shinto is the "clean religion". white is pure, and so on... We wear a Hakama at 5th Kyu, which can take up to 2 years to get to. some wear green, blue, black, or off-white hakamas.
Would you say that it's individual which color a person can use on his/her's hakama? And do the colors represent anything in shinto(don't know anything about shinto)?
Not sure about if/when/how/why some of the Hakamas are different colors. it could have to do with rank. I have only been doing Aiki for 2 years, and am about 6-8 or so away from Shodan. as for Shinto colors, usually there isnt specific colors, but White is the most often seen color in Shinto. that and Blue (the color of my skin after winter Misogi Shu ho.........lol)