So this thing’s been in Super Robot Wars a couple of times so it’s probably less obscure outside of Japan than it could be, but this is Jaku Satan, the crystalline mecha of the villains from the Raijin-Oh anime, which I watched (sans any form of English translation) recently.
And I found myself wondering...
...did it influence Power Giant from Yu-Gi-Oh! 5D’s?
Certainly, the physical design is pretty different-Power Giant has far more conventional anatomy-but look at the shapes of the protruding crystals on the shoulders, arms and knees of Power Giant versus the chest and back crystals on Jaku Satan. And hey, looking again Power Giant has a back protrusion.
I’d doubt the connection, but based on things I’d been familiar with already, when I started watching the Eldran series (of which Raijin-Oh is a part) I noticed that there were a pretty fair number of things that Eldran could very plausibly have been a significant influence on. Most of it tokusatsu, admittedly (all three of the Eldran series are sentai tribute shows to one degree or another, and it’s interesting that it looks like there was a reverse influence), but there were also possible influences on later Sunrise anime, including the second half of the Brave series and Gear Fighter Dendoh. (I’m considering doing a post or so on this later, which is why I’m not really going into it now.)
(Screenshots from a random mid-range episode of Zettai Muteki/Matchless Raijin-Oh; I don’t feel the need to be more specific because this was stock footage. Power Giant image from the official website through the Yu-Gi-Oh! wiki.)