It's been half a year since Kaiju went to see a behaviorist for his fearfulness. We have been in touch with her (who happens to be from Japan and very familiar with Shiba Inus) every few weeks to report back the progresses Kaiju made, or mostly lack of it. Kaiju has been put on medication since then, called Buspirone. He has also been completely free to roam around anywhere in the apartment even when we are not here. This was a big change. We used to put him in a small gated area whenever we left him alone at home. She told us to let him explore, make up his own mind, and the most awesome for Kaiju of all, be naughty.
Six months later, he is no longer afraid of paper bags that we bring home from grocery stores (he now sticks his head in them), or the random objects that are in foyer right outside of our door, such as UPS packages for other residents and newspapers. He now goes in to the bathroom to sniff around all on his own, whereas we couldn't even lure him into it with treats before. Outside, he no longer panics and flees when people come out of apartment buildings, and he can walk past trash bins without making big half-circles around them. He seems okay with strollers and rolling bags, too. These days, he sniffs around a lot while walking which he didn't do before because he was too nervous. He is often too nervous to take treats from us during walks, but these days, he is more frequently relaxed enough to not only take treats, but also look at us to ask for them. He even wags his tail a tiny bit once in a while while he is at it.