>>6267833The square stand is included with all the SAS Kinnikuman figures, I believe.
There's also the 3-hole bases that can fit together to make a 6-hole base. That and the smaller stand that comes with Koichi is what I used to make the part 4 display and I highly recommend against it because it's very limited and you have to meticulously balance everything because the base plate will tip if the weight is off.
Here's a pic I just took of my current setup so you can see what a shitstorm of display arms it is inside. I hadn't touched my display in so long I totally forgot CD was just kind of resting in the middle because I couldn't maneuver an arm to support him.
>>6267834That's exactly what it is.
>>6267851The SAS display arms also fit into the figma stands fairly well, so a di:stage might be a good alternative. They can be equally as hard to find as the 6-hole bases, though.