The Mystery of Tube's Inhabitants in Maskman

I recently find myself crossed with the mystery of Tube. Okay Maskman was a great series but I think Tube somehow had an unsolved mystery concerning its people. So here are a few things we know about Tube's inhabitants is that they lived underground and they hate the sunlight. In fact some stuff from Tube would later disintegrate when exposed to the sun like the power rolls or the shinobi ball. But what was not just about it, here are a few things I consider to be plotholes:

1.) If the people of Tube hate sunlight then did Princess Ial during her spying mission ever have some way to prevent damage to herself? Perhaps she retreated every once in a while to rejuvenate herself.

2.) About the underground monsters- do they really have shorter limits under the sun before they get hurt? They hibernate under cold temperatures.

3.) There was one member of the underground who later lived on the surface world from the Mereru tribe. Did she adapt to the sunlight soon? The fact that she frequently wore long clothing is not enough to prove my theory.  Long clothing for both men and women are common in cold countries.

Apparently, they can't stay under the sun for too long seeing that Emperor Zeba wants to turn the surface world into a dark, cold place which is mentioned to suit their living conditions. I kind of thought that perhaps these plotholes led to the creation of the Gedoushu in Shinkenger but that's all purely speculative.