If I'm not mistaken, it's a vinyl... it could be one of the Mega Kaiyodo kits from the early '90s, as the sculpt closely resembles that of Mazinger-Z's kit sculpt by the design and look of some of the body parts.
Or perhaps made by the same artist at eBay who made several vinyl kits of other super robots and mechas, including a 20" Mazinger-Z kit...
This Mazinger-Z kit, particularly, looks like a knockoff rendition of the vintage Mega Kaiyodo No.1 1/100-scale Mazinger-Z kit which was manufactured back in '94 and sculpted by Takuma Katsuo. It is supposedly "rare", but is becoming a little pricey on eBay.
Here is the actual Mega Kaiyodo No.1 1/100-scale Mazinger-Z kit... (wish it were mine! lol)
In any case, if any of these other kits are knockoffs of the Mega Kaiyodo kits, they sure look SchwEEt super-cool as they are!
Heavy, thick vinyl. If it's a KO, it's a good one. I was told it's a Colorways kit. I've looked at a few of the ones on ebay, looking at the feedback of the sellers, they're really thin. This one actually has 15 movable joints with the only glued on pieces being the cape and head. I really had a blast with it and looking forward to finding another!!
What kind of paint are you using for that material?*****
(Whenever I see those figures with that type of body-part connection into the holes and sockets, I had always believed that the parts would have to be softened in hot water or a hair dryer so they'll flex into the holes.)
*****I'm planning to get the 20" Maz figure- the one shown above-- ---every time I look at it I'm thinking I should assemble it first, and then paint it.
*****In the past, I painted a Great Mazinger jumbo head (detached from the body)... I sanded it and then hand-painted it with Rustoleum colors. Then I trimmed some of the edges off the neck base so that I could re-attach the head to the body without having to wrestle it back into the hole, or else the paint would have cracked. I still have a couple other jumbos to paint, and of course their softer pliable parts as well.
This thing was a blast!! I tried a Lowe's, Valspar, paint and primer in one first, just to see how well it would hold. After cleaning the parts really well, it held great! I then softened the joints with a hair dryer to get them into place and hand painted the rest with enamel model paint. Now I'll try to track down a glossy clear finish that will work to seal it.