This is one of those things that shifts a little in Japan - there are generally 3 variations of hun soul and 7 of po, but exactly what they are varies depending upon who you speak to. I didn't go into that very much.
The same character for "intent" exists in Japanese - but Ueshiba didn't use it much, although he clearly talks about intent in many places. Maybe that would have been too easy to understand...
That is very interesting - the 3 hun and 7 po go back to China, as they are discussed in early Daoist texts. I didn't realize that part of the imagery had survived in Japan as well, though I guess I shouldn't be surprised.
Is the usage of hun as being equivalent to yi/intent common in Japan? I've never come across that before. Though I haven't looked very hard.