This picture of O'Sensei, and Doshu in the shadows, looks like shin kokyu practice, as we call it.
I think he's telling a story about a watermelon and Doshu is clapping...
That's a joke.
Shin kokyu would be an interesting place to apply some internal body skills and/or pick Anno Sensei's brain about. There's a lot in there, or at least those movements have a lot of potential, IMHO.