In Boukenger, the Yellow color is represented by Natsuki Mamiya, alias Bouken Yellow.
As the Boukenger storyline progresses we find out that she's not an actual human, but rather, a Princess of a lost civilization, Lemuria. This is the picture of her parents back in the past:
Yep, they're played by Sentai alumnus, in particular Keisuke Tsuchiya (Kazu/Kirin Ranger - Dairanger) and Eri Tanaka (Chisato Jougasaki/Mega Yellow - Megaranger). They're both of Yellow colors, so people might think this as some sort of Mythology Gag or Shout Out. But... Yellow? Lemuria? Le-MU-ria? Don't we have something similar like that in the past?
Well as you can see, apparently that was indirectly shouting out back to Goggle V, in particular Goggle Yellow. It was very skippable because while ancient civilizations were mentioned as a motif, it was limited to just the forehead symbol of the Goggle V and we didn't really dig into the myth of these civilizations. Would be nice, though, but I guess that's how it goes in older Sentai (even in Changeman, despite having a mythical creature theme don't really spend time on the mythology of these creatures). So yeah, we have a Yellow ranger who had 'connection' with Lemuria in the past, so maybe that's why they pick Lemuria as Natsuki's civilization of origin. It's too bad that Sanpei Godai (Futoshi Kijima's actor) wasn't present to become something like Lemurian King or something, would've made it full circle and I heard that he along with Junichi Haruta were the only remaining actors in Goggle V that are still into acting. Pity indeed, but I'm not gonna complain. That and this is mostly unknown because people tend to forget classic Sentais NOT called Goranger (or JAKQ, because of Big One), so they didn't realize.
But regardless, I did say 'possibly' because this might not as it seems. Professor Hongo explicitly said that the Opal represents Mu continent, and if you see through the links of Wikipedia, Mu and Lemuria got separate articles, and perhaps they ARE different civilization. However, one thing that we can get is that they're both hypothetical and lost continents, thus it makes sense when you think about it.
But regardless, I do say that this is an overlooked piece from a rather unknown, classic Sentai series. I hope this shed you enough knowledge. I'll be seeing you later!