I have recently learned about this committee for the first time. Maｙbe, it has been to my ears in the past. But I have never realized how it had worked on the politics/economy in Japan.
It has started immediately since the WWII was over. While japanese members of this committee are the top bureaucrats in Japan, the US side is composed of military people except for the US minister as the only non military diplomat. The meeting has been closed keeping the agenda in secret. The main agenda has been regarding the US base and its military operation. It seems they have discussed of diverse issues there. The State Department in the US has been repeatedly recommended the US military to convert the system to the ordinary diplomatic relationship. The US military has been denying that. One reason is that Japanese government won't agree to undertake the change. This system seems profitable for both US military as well as Japanese bureaucrats. Yes, the occupation of Japan by US military after WWII is still continuing. It has been over 70 years ever since.
"The collective self defense" our government has established against our constitution last summer has been based on the requirement by the US military to join military conflicts all over the world lead by the US military. Most likely, this requirement has been done at this committee. The other issues in relation with the US could be understood from the perspective of presence of this committee.
I wonder if our country is really independent under such a system. At present, unfortunately, we could not affirm of independence at all. Such a system would lead the relationship between Japan and the US toward undesirable way, I am afraid. I wonder how you Americans think of such a relationship like a suzerain and a colony. It is a reality that our Japan has enjoyed prosperity and no involvement in any military conflict or war thanks to this relationship, at least, partially thanks to it. But I think this relationship would be against fairness and equality.