He's already making big strides forward with his harness. He is happy to see it when I take it out, and he seems to like when I clip the neck strap into place (because he gets lots of treats). That's as far as I've taken it - I've learned that it's much better to go more slowly than I think is necessary than to go too fast.
I've started a course on therapeutic play with Hachi. It's a course that I took a few years ago with Shyla, and it made a big difference in helping her to let down her guard. I already can feel my bond with Hachi growing stronger from playing together twice per day. The goal is to use play to help Hachi to relax in environments that he currently thinks are scary.
Shyla already knows how to play with Hachi!