*BURP* Holly's cheeks flushed as she covered her mouth from a large burp.

"I guess I ate too fast..." she thought before patting her slightly distended belly.

Getting up from the table, Holly placed her dishes in the dishwasher before heading back upstairs to her bedroom.

Grabbing a change of clothes from her bedroom, she made her way back into the bathroom and proceeded to strip for the shower.

The hot water raining down on her body always felt great, as if she were washing away the grime of the previous night, and as such she often took fairly long showers.

Feeling an itch in her left breast, she cupped it in her hand, rubbing it lightly.

She was a C-cup breast, but in spite of her age she was still growing. In fact, she had been a B-cup only a mere 5 years prior!

Holly shifted slightly in the shower as the itch in her breast turned into a pleasant tickle. Her nipples began to perk up as her as her crotch began to feel a bit warm. She was always so sensitive to external touch, but she still had so much to do today that she couldn't afford to satisfy her sexual hunger yet.

Grabbing her washcloth, her pussy gave one last pleading shiver as she ran the cloth along her hardened nipples, however, Holly managed to ignore it.

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"Is everything alright?!" The foreman called out as a team of maintenance workers examined the pumps.

"Damage is minimal!" one repairman called out causing the collective to give a sigh of relief.

Tremors were a frequent occurrence in these tunnels. The tunnels were located in the center of two massive twin hills which seemed to have terrain far softer than any other part of the planet. Due to the weak structural integrity of these hills, they often swayed and bounced with the movements of the planet's erratic orbit. Sometimes the planet would also collide with itself moving the hills violently this way and that, but all of these movements were usually fairly predictable and as such they could shut down the machinery before they occurred.

The rare occasion that unexpected tremors did take place, a thorough check would have to be done of each of the pumps just to make sure nothing had been knocked loose. However, even unexpected tremors happened frequently enough for the crew to have the emergency procedures down to a science so it wouldn't take long before the massive pumps were running again.

The only openings to the surface on the planet's two massive twin hills was located at their very tops. The terrain here was different from the rest of the hill and topography would change frequently, sometimes letting the entrance be at ground level, and some times raising the entrance onto the top of a steep unscaleable cliff.

Inside the hills lay a network of tunnels all branching off from one enormous main tube. While this tube was not near as large as the hot springs, acid ocean, medical or waste caverns, there were still numerous bustling cities that had been established over the years in either of the twin hills.

The main export of these cities was the milk which could only be found in the underground lakes that filled the hills. Each tunnel that branched off from the main tube eventually led to a massive hollow underground reservoir of milk, each one large enough to dock an entire fleet of ships.

The milk would be pumped out by each city and then shipped via the submarines travelling the underground red rivers to other colonies across the planet. However, there was such an abundance of milk, that the hills had also become a bit of a tourist destination, boasting lakeside lodges built into the walls of the massive milk cisterns that visitors could go to for boating, swimming, or simply enjoying the view.

The lodges had to be specially built to withstand the rough waters that often occurred during the hills' more serious tremors, however the sights were beautiful and the fresh milk so delicious that many felt it to be worth the risk.

Even residents of the cities in the main tunnels often scooped up prime milkside real estate for their summer homes.