Disclaimer: Neptunia franchise belongs to Idea Factory.

The Past best left Untold

It was another normal day at Planeptune, the city was filled with people and everything was running well as they should be. Even inside the basilicom, Histoire the Oracle has put everything into order and work was being done all around. Yes, even Neptune was outside doing some work to uphold the nation, which pleased Histoire greatly.

With all the workload handled, Nepgear was free to do as she pleased. Even though she herself wanted to spend some time with Neptune, but seeing her elder sister was working for the nation (for once) was also a good thing. Luckily for Nepgear, Uni had a bit of free time and so the two of them decided to take a stroll through the Virtua Forest Depths, having a relaxing chat on the way.

"So in the end, we really aren't doing anything much besides walk?" Uni asked, seeing as how a lot of times when she would spend time with Nepgear, the idea of where or what to do just does not come naturally.

"I guess so, but at least spending time with each other is fine right?" Nepgear responded, also knowing that with how Uni and herself were, they tend to spend more time talking rather than having a certain activity they did together.

"Well, I guess we could talk about the things we wonder about."

"Oh, like a mystery? Some things of the world are interesting, I read about some pretty interesting things back at the Planeptune library before."

"...I was thinking of something more personal, like why my sister doesn't have any friends."

"Eh... I am not sure why, she seemed friendly the few times I have talked with her. Though... now that you mention it, I wonder how my sister is able to uphold Planeptune all the time when she avoids work all the time..."

"Right? Sometimes I wonder if there is something that our sisters are not telling us, like a dark secret."

"I don't think they would be hiding something serious from us, especially when-" Nepgear said, before tripping over something and falling over.

"Nepgear! What happened?" Uni asked, while going ovr to her fallen friend.

"I felt like I just hit something hard with my foot," Nepgear responded, then looking back to see what appears to be a handle.

"What's this?"

Reaching out to feel the object, they felt that it was metallic, and pulling on the handle they felt great resistance. Clearly though, this was a hatch door, concealed by the mud and dirt to blend in with the forest so that nobody would notice. Slowly, both Nepgear and Uni brushed away the dirt and revealed the full size of the door, it was big enough to fit a person through for sure. Without the debris in the way, they pulled up the hatch door and through the darkness, they noticed a flight of stairs down underground.

"Stairs? Where could this lead to?" Nepgear asked the rhetorical question, unsure of what to expect with this discovery.

"Should we go down and find out?" Uni responded, at least a bit curious with the suspicious find in the middle of a forest.

Carefully stepping in, both of them walked down the stairs with caution, not knowing what to expect. There was enough natural light from the opening that they had not need a flashlight, and upon reaching the bottom, they could see a sealed door, with the famous purple "N" imprinted on the door along with a card reader to its right.

"This is something that belongs to Planeptune? But I've never heard of such a place before..." Nepgear said, before reaching her key card, thinking that with her privileges as a CPU Candidate should be enough to grant access.

Uni also watched in anticipation, there was just something rather off and suspicious for somebody to hide something underground here in the middle of Virtua Forest Depths. Whatever was on the other side of the door might just be a dark secret, and even though she had mentioned it earlier, Uni hoped this was not actually the case. Nepgear swiped her card through the lock, and it actually worked, the door unlocking and slowly opening by itself as the two began to venture into the unknown.

Back at Planeptune, Histoire immediately felt a disturbance. Quickly looking over at one of her monitors and verifying where the disturbance came from, her eyes widened.

"(Who could have found that place?)" Histoire thought, alerted at the fact that somebody is accessing a place where they should not, and even though things were running well in Planeptune today with Neptune outside working for once, she was ready to make an emergency call.

Stepping into the room, Nepgear and Uni saw the blue lights and the few work station with chairs lined up across the room. It was a normal room for synthesis, very typical and looked like it had not been used for quite some time as evident by the dust. However, the place did have power to it, due to the lights and the slight humming of machinery. As soon as they entered the room though, the door slowly closed on them and sealed shut, with no sign of being able to be opened again.

"Looks like an old production lab and nothing more," Uni said, a little relieved but was concerned about the closed door behind them.

However, Nepgear noticed another door at the end of this room, which was the same as the first door. "I wonder what's beyond that door..." She said, although this room was normal, Nepgear had a feeling of dread, of something that did not feel right about this place.

"It's probably nothing right?" Uni responded, a little afraid of what could happen.

"I am curious though, why would my nation hide a place like this down here? And..." Nepgear trailed off, looking behind at the closed door from where they came in from, knowing that there is only one way to go.

Taking a deep breathe, both CPU Candidates walked towards the next door, also noticing a box of trash-mainly broken test tubes and bottles. Nepgear unlocked the door as they walked into the next room. Upon entering this room, a cold atmosphere enveloped them, and the dimmer lights in this room made the feeling of dread much worse.

After looking around, they realised this room was anything but pleasant, it was a room for storing specimens, with preservative tanks lined up across the left side of the room. Taking a few steps forward, Nepgear noticed something... unusual. Upon realising what was in one of the preservative tanks, she paused and gasped. Uni noticed the same thing and also froze.

In the tank just second from the left was a disembodied Fenrir head, just floating there. Nepgear and Uni wanted to scream, but fear had crippled them too much, they could only drop down on the cold hard floor to breathe.

"W-what is this? Why is such a place in Planeptune?" Nepgear said, horrified at what she was seeing in this room.

Meanwhile, Uni looked to the right and was shocked again, there was a dissection table, with all utensils ready to use, though the place was well maintained and there was no sign of either blood or biowaste, it was still not something that she would like to see. After regaining their composure, Uni turned around and inspected the door from the entrance, this place was clearly not safe for obvious reasons, and there had to be a way out. Except there was no way out.

"The door won't budge..."

Nepgear has also gotten up by now and was looking to see if there was a way to unlock the door from this side, but nothing was found, they were trapped. Both of them could only scan the room, and with the cold temperatures enveloping them, fear also began to crept in, and they could almost feel as if the specimens from the left were gazing into their soul from within their tanks.

Nepgear looked towards the end of the room, there was yet another door leading to a third room. The two looked at each other, they had no choice but to move forward like this, the cold was enough to drive anybody insane, let alone the specimens still preserved within the tanks.

Holding hands, the pair gathered courage and walked forward down the middle of the room while looking down on the floor, they had no desire to take another look at the Fenrir head, other specimens, nor the dissection table. Finally reaching the end, Nepgear unlocked the door with shaky hands, hoping that there would be an exit to this nightmarish place.

As they walked through the door, they entered a hallway. While it was not cold like the previous room, this hallway barely had any lights, and the brightest light came from the end of the hallway from yet one more door, and this door looked much bulkier than the ones before. With no other choice, the pair continued onwards and reached the door. unlocking this door, they entered what they hoped was the final room and an exit.

Inside this room was barely any lights, but the lights that were present were white light bulbs instead of the creepy blue they had been used to at this point. They could barely see what was in this room, but there was a large pool of green liquid to the right side of the room, while the left side had a huge storage case, full of test tubes and bottles neatly arranged and sealed.

In front of the storage case was a table with a few microscopes and burners, along with other empty beakers. All the equipment still had power, which was a cause for concern, whoever this lab belonged to, was probably around here somewhere.

Seeing so many test tubes, the two observed the shelves for labels, and they found Reflex, Paralaxin, and Tuffmil bottles, which seemed normal enough. However, the lower shelves had names that they could not pronounce or figure out, but one thing was certain.

"It's poison. All of these..." Uni said, realising that the bubbling and colour of the bottles it would suggest so.

"Goodness... Who did all this?" Nepgear said, knowing that somebody is hiding their lab down here in Planeptune and developing some rather dangerous creations.

The far end of the room had no door this time, but instead the wall seems to have some sort of display case, though it was covered so none of the contents could be seen. There was two of them, one higher and one just underneath it.

Nepgear and Uni could not believe it, they just found a lab full of horrors scarier than Arfoire, and they were trapped, with no way to contact the outside world to rescue them, and if whoever owned the lab and caught them here, the horror would be unimaginable.

Still, since there was no way out of here, they could only sit down on the floor, hoping to wake up and away from this bad nightmare. The door to this room remained open, but the door that lead them from the previous room and into the hallway was closed shut.

After about 20 minutes of deafening silence and not much talk due to fear, the paranoia and distrust set in. Uni walked to the middle of the room, loaded her gun in ready for defence.

"Uni?" Nepgear called, hearing the sound of the gun being loaded.

Turning around, Uni pointed her gun right at Nepgear, while shaking in fear. "S-stay back... This place belongs to Planeptune right? And you even have the key to this place, this is all your doing isn't it?"

"What? No, I... Would never do something like this!" Nepgear protested, knowing that while it was odd that her card key worked, this is something that she would never do.

"Stay back!" Uni said again, shaking in fear, not knowing what was going on.

While the pair got caught up in their conversation, they failed to notice the door from the specimen room open, and along with footsteps approaching their location.

"All right, put the gun down." Said the foreign voice, while a figure stood at the open doorway.

Nepgear and Uni slowly turned their heads to the source of the voice, there was finally somebody else in here, but was it salvation or was it a harbinger of doom?

"Oh geez, I had expected some unlucky travellers to wander in here, I never thought it was you two. Ah right, this room could use a little bit more lights." The person said, reaching into a pocket and handling a switch, lightening up the entire room.

The light blinded both Nepgear and Uni for a little bit, but when they adjusted, they looked towards the new person, it was somebody about the same size and height as they were, dressed in a large white lab coat. They recognised the face however, with the short lilac hair and the two white d-clips.

"Neptune!" They said, surprised at seeing Planeptune's CPU here in this form, as well as having many questions.

"Hey there both of you, welcome to my lab I suppose."

"Wait, this is your lab? Everything here..." Nepgear responded, now a little fearful at this revelation.

"Yup, all poison and specimens here belong to me." Neptune responded, not changing her expression.

"Wait, why though..." Uni asked, also shocked that the bumbling CPU of Planeptune had something as sinister as this lab underground.

"Well, it's a long story, but way back when things weren't so friendly between Planeptune and the other nations, I needed a secret weapon to secure the future."

"Secure... The future?" Nepgear repeated, still in disbelief her sister owned such a dangerous lab as well as a dark secret that even she did not know about.

"Yep, and in those display cases are my greatest and most potent poisons..." Neptune responded, walking towards the end of the room with the displays.

Flipping another switch, the upper case was slowly being unveiled, and from where Nepgear and Uni could see, it was a simple but scary sight. There were three bottles of poison there, normal enough. However, the three bottles of poison was coloured on purpose: one green, one black, and one white. They realised what or who those were intended for just looking at it.

"Wait Neptune, you didn't plan to..." Nepgear protested, unwilling to believe her sister would have planned something so malicious.

"That's just the thing with war, there's no such thing as going too far, the four of us hated each other from that time, we weren't always like how we were..."

Uni was at a loss for words, if what Neptune said was truth, then surely Noire would have told her... Yet, if this was a dark secret from the past of the four CPUs, then it would make sense to conceal it. Still, the one thing that bothered Uni was the lower display case, and even though she knows better, she spoke anyway.

"What's... In that other... Display?"

"This one? Well, there's such a thing as curiosity killed the cat or whatever right? Still, I guess I can show you, these were a just-in-case situation, but..." Neptune responded, flipping another switch and opening the lower display case.

Uni had wished she did not ask, but the lower case had four bottles of poison this time, and the colours were: light blue, light pink, gray, and violet.

Nepgear and Uni only stared at the lower display, this was more horrifying than the specimens from the earlier room, they could not understand or comprehend this at all, and were speechless at the implications of what they were looking at.

After a few moments of blank stares, Neptune sighed and began again, "Oh well, I had always planned to keep this a secret, so guess this may be the only way..."

Neptune pulled the pin of the canister she was holding in her hand and threw it between Nepgear and Uni, the canister exploding instantly with a gas. With no time to react and the gas quickly paralysing the two of them, they gradually slumped down onto the floor while coughing up what seemed to be the last of their life.

"Neptune..." Nepgear muttered, while slowly losing consciousness as despair had set in on what her and Uni's fate may be when they wake up, or probably it would be better if they never woke up.

After some unknown time, Nepgear felt a nudging, and also a voice. She could not recognise what was going on, but she felt that she was being forced out of her unconsciousness.

"Nep Jr! Wake up already! And same to you, little Noire!" Said Neptune's voice.

Slowly opening her eyes, Nepgear was greeted by the night sky from Virtua Forest Depths. Sitting up, she noticed Neptune with her usual hoodie dress by her side and Uni getting up as well.

"Geez you two! Napping in the middle of the forest like this isn't quite safe you know?" Neptune said, looking at the tired Uni and Nepgear.

"Huh? We fell asleep? And it's already dark!" Uni exclaimed, notcing the night sky and realising that she was supposed to be back home before.

"Yeah, I dunno how long you guys were out for, but don't worry! I told Noire you can spend the night over here with Nep Jr, so if you sleepyheads are not too tired, let's go!"

"Um all right..." Nepgear responded, unsure of how she fell asleep with Uni in the forest and for such a time that it would be night time already. It was just the afternoon when she was walking around with Uni, but she could simply not remember sleeping from that point onwards.

Back at Planeptune, Nepgear was getting ready to sleep for real, and in the comfort of her own bed at that. After some pudding snacks and a little bit of video gaming, she and Uni were ready to sleep. Neptune had cleared the upper bunk bed that belonged to her and offered Uni the place to rest for the night. When the lights went off, there was relief, certainly being woken up in the middle of the forest was concerning, but at least nothing happened to them.

"Geez, we wasted half the day just napping..." Uni said, not really liking the idea of spending the day that way when she was used to working instead.

Nepgear giggled a bit, Uni was much different than her in this regard, but was still a bit pleased with this result. "Well, when I usually go out with Neptune, we ended up doing the same thing too, but it's not too bad honestly, we did spend some time together."

"I guess... Well, good night Nepgear."

"Good night Uni."

Outside on the balcony, Neptune stood there, looking towards the direction of her underground lab while Histoire appeared after finishing her work for the day.

"So it was those two that found your lab..." Histoire said, floating beside Neptune while relaxing after the day's events.

"Yeah... I didn't expect that, but I still fixed up the whole situation good," Neptune responded, giving way to a sad smile.

"Do they still remember what they saw?"

"Nope, the gas I used was to make sure that they were safely asleep, then I used a special formula that completely wipes out that part of their memories."

"I see... I had hoped that I did not need to call you back so early today."

"It's fine Histy, rather thanks for letting me know."

"You know we cannot hide this truth forever..."

"I know. But this is just one of those things that I'd rather not bring up at all if we can. Those were the worst times in history after all."

"That is true. The four of you Goddesses had such an intense hate for each other that war simply meant destroying each other completely, and you of all people chose biological warfare combined with your studies in toxicology."

"It's not only me though, surely you know about Vert's Sky Bombers, or Blanc's Submarines, or... even Noire's Nuclear Missile... At least nowadays I mainly specialise in making Nep Bulls instead of poison."

"I am glad the four of you eventually found peace with each other, Gamindustri would have not survived with the methods the four of you were using for fighting."

"Yup, that and the fact that Nep Jr. and the others came along, we sorta didn't want to expose our precious sisters to such horrors of war. Even if they were caught up in the battle with ASIC, it still pales in comparison to what we did."

"The CPU Candidates are a blessing to us all indeed."

"Ah yeah, and nowadays, I just act like a dork while you lecture me to get to work, and Noire acts strict and diligent to keep herself busy, Blanc is just some cute grump, and Vert is an MMO addict... Hehe, sometimes I think we've acted those roles long enough that we've become what we were acting to be."

"That would not be good, especially if you've actually become lazy Neptune."

"Nah, no way... I'll complete my daily quests so I can appear to be lazily sleeping in when morning comes." Neptune finished, transforming into her Purple Heart form and flying off.

Histoire closed her eyes in thought, she knew that one day the CPU Candidates would hear about the past sins of the current CPUs, and she could only hope the loving bonds between them would carry through even the most ugly truths in history. Histoire may be the tomb that records all of history, but she knows that sometimes certain things are better left untold.

This is a 'what-if' idea on how the four CPUs might have acted in war like in the first HDN but in the setting of mk2 and the possible reaction of characters reacting to supposed dark secrets.