Disclaimer: IF/CH has the rights to HDN franchise, but here's hoping that they would expand on some of the lore soon.
Chapter 1: Insecure Feeling
A few weeks passed by with peace settling down in the world that is Gamindustri. Of course, the four nations and their CPUs have slowly went back to their daily lives as usual, except this time they also had more friends because of their latest adventure through the dimensions along with a rewrite. Most importantly though, the one known as Uzume Tennouboshi was alive and well within the Hyperdimension while exploring the land. Travelling alongside her is the Adult Neptune, who had nothing better to do but eat pudding and other delicacies in this dimension.
Unlike the Adult Neptune, who was free to do whatever she wishes to do, the other Neptune-the CPU... also liked to do whatever she wishes. However, being a CPU in the times after conflict meant that there had to be tons of work done. While slacking off from the CPU was expected and not all surprising, the Oracle Histoire still had a bit of trouble keeping that Neptune on task. Both Uzume and the Adult Neptune were not surprised by this fact either, they often made Planeptune their home given their own unique history with the city. Sometimes, Uzume did worry for the future of Planeptune with the way Neptune handles everything, but she was not one to really say much given that she would have done mostly the same things as Neptune.
Yet, that was the main point of interest. Now that Uzume has had some time to "catch up" on the technological, social, economic, and political updates to the Hyperdimension, she began to turn her attention to the history of Planeptune, the nation that she so loved. After all, just how did the nation do after she disappeared? What happened to Uranus? And most importantly, when did Neptune become the CPU? The answers must all lie within the history of Planeptune. Naturally, the best source of information for history, and especially dealing with Planeptune, would involve Histoire. As Uzume opened the door, she clearly saw that Histoire had to give Neptune another lecture on skipping out on working as a CPU again.
"Uzume! You've come to save me!" Neptune exclaimed, running away from Histoire already.
"Hey Nepsy, good to see you're doing well!" Uzume replied, nothing better than seeing the current CPU ever so happy compared to her reign.
"Neptune! I am not finished here," Histoire said from the other end of the room, clearly not impressed with Neptune's attitude towards work as always.
"Ah Histoire, there's no need to keep going at it for too long. After all, even I didn't work every single day when I was ruling over Planeptune."
"Yes, but you do know Uzume, unlike you, Neptune wouldn't work unless I tell her to, especially when Gamindustri is rebuilding right now."
"I am sure it'll be fine, I hear that Nepsy handled it well during that shift period, right?"
"Yep! We've worked about 10 years worth of work in that last adventure, so let's get some pudding to relax!" Neptune replied, now running out of the room and getting way further away from Histoire.
"Oh dear, why do all of Planeptune's CPUs always end up like this?"
"Haha, maybe it's just how it is. Actually Histoire, that's why I have come here today. I have seen many great things as I travelled around this world for awhile now, but I am actually interested in finding out the history of this place after I sealed away myself."
"Very well... follow me," Histoire replied, leading Uzume to a library in the back.
In the very space of the room, there were some tombs that were similar to the one that Histoire was sitting on, all neatly organised and arranged. This was surprising for Uzume, it would appear Histoire had kept going about her function with recording history all this time. For Uzume, this place felt nostalgic, almost as if all the history within the tombs was home, as well as a direct connection between her and then current world.
"Here we are, this is what I have gathered throughout time. However, even I do not necessarily remember every single detail recorded, but should you have something you need, I will try to assist you."
"Thank you Histoire, this will be great, finding out what has happened!"
Uzume had taken a few tombs, some of it were recorded history of Planeptune while others were world history to give the situation context. Like most Planeptune CPUs, Uzume usually had no interest for something like sitting still (with the exception of napping) and reading or such, but after running around for a few weeks had her curious about Planeptune. It also came at a good time too, since the Adult Neptune had decided to drop in and visit her home in Ultradimension Planeptune (Uzume went with her once, but then got PTSD upon seeing the CPU there transform). Obviously CPU Neptune had work and Nepgear was probably at also work or making her next wacky invention, and so it left Uzume all the time in the world. Finally diving into the history of the era just after her time, Uzume reads through the history of Planeptune:
"Gamindustri, land of the four nations of Planeptune, Lastation, Lowee, and Leanbox ruled by their own CPUs Magenta Heart, Blue Heart, Red Heart, and Viridian Heart respectively. In this era, the nations were always competing for global supremacy and often kept to themselves. Peace was very far and between, as the CPUs never had a good stable relationship with each other. Yet, the general populace often lived in peace within their respective nations without too much conflict unless it was the rare time the nations went out to war directly against each other. However, each time war broke out, it never lasted for too long as the CPUs understand that a long war of attrition will completely erode the land and claim too many lives of people, who gave their faith in share power to the CPUs. Still, war raged on over time, and there are also a fifth group of people, ones who never pledge themselves to any CPU and instead lived away from the rest of civilisation.
Unfortunately, the groups that lived away from the nations eventually grew bigger than any one nation due to the constant war between the CPUs, and eventually these people formed the Arfoire Syndicate of International Crime (ASIC). In spite of this though, the CPUs only found ASIC as a mere annoyance rather than a threat. Only on some occasions did the CPUs band together to get rid of the more troublesome activities of ASIC and cripple them, but they never truly went out of the way to completely destroy ASIC, as whenever ASIC was on the verge of destruction, one nation would always betray the trust of another, causing enough of a distraction for ASIC to live on. Yet, there was one nation that had constantly been considered the 'victor' of each skirmish, and it was Planeptune. Using their advanced technology and Histoire's stratagems, Planeptune's shares would inflate despite losses on certain occasions.
This has not gone unnoticed though, as Lastation, Lowee, and Leanbox eventually saw the disparity in shares, they would be more than willing to team up to ensure survival as well the toppling over Planeptune. Meanwhile though, with the excess in shares, the CPU Uranus began to look for new options to help end the war as well as defeat ASIC. Finding a possible solution, Uranus and Histoire began a project that would soon revolutionise Gamindustri, as they gathered enough shares and condensed them into a single sharicite, they had done what nobody had done before: Gave rise to an entity known as a CPU Candidate."
The records and summary notes ended at that point, in which Uzume had mixed feelings. Even though she was happy that Histoire and Uranus had lead Planeptune into prosperity, it was also disheartening to hear that the CPUs of that era bicker and fight to the point of unable to set their differences aside to truly defeat a common enemy completely. Still, eager to find out what happened next, Uzume gathered and reached for the next series of tombs that would explain what happened after the creation of the first CPU Candidate. However, the next pieces of history that she read was quite different than what she had been expecting...
"Gamindustri. A peaceful land where the four nations of Planeptune, Lastation, Lowee, and Leanbox stood tall and provided for the people. The CPUs lived in relative peace with each other as Purple Heart, Black Heart, White Heart, and Green Heart proudly represented their respective nations. Hey wait a second, did I grab the wrong volume?" Uzume questioned, seeing as how the history she was reading did not match where she left off. However, upon inspecting the library again, what she read was indeed the direct continuation of what she had read earlier, much to her surprise.
Uzume was clearly confused, about half-way through the reign of Uranus, it was as if history had stopped recording, and the current history she was reading was already telling of Purple Heart, who was clearly Neptune. Still, it was not even the beginning of Neptune's reign, it was probably years or some time after she became the CPU, as there was no longer any mention of Uranus or the previous fight with ASIC. By this time, Umio had entered the room to bring Uzume some tea, having heard of the first Planeptune's CPU settling down to catch up on recent history.
"Uzume? You look like you're troubled, is something the matter?" Umio asked.
"Umio! Ah, I was only going through with what happened after I was sealed away with Planeptune's history, but... it seems like there is a huge piece of history missing here for some reason," Uzume explained, showing the two volume of tombs from Histoire and the disparity of setting.
"Hmm, I see... that is rather strange. Histoire should have perfectly recorded everything, so there's no reason for this... perhaps we should try asking her about this?"
"Yeah, that's probably the best. It's like watching until the climax of your favourite anime and coming back next week just to see filler."
Still, Uzume was grateful for Umio's hospitality and enjoyed some tea along with pudding (from a little somebody of course) then went back to Histoire for a moment and explained the fragmented history.
"Hmm, this is..." Histoire trailed off, unsure of what to make of this whole thing.
"Do you not remember as well? That's all right, I mean, when you record so much, maybe you fell asleep at one point or got tired of it..." Uzume responded, thinking maybe even Histoire is not infallible.
"No, I am quite sure I should have... however, unlike forgetting about past events, I simply have no recollection of that time..."
"What, really?"
"Unfortunately, it would appear that way. Now that you mention it, I don't think I remembered how I met Neptune as well, even though I have always thought that I was involved with her affairs. For this case, I would have said we should ask Uranus directly."
"Wait, ask her directly? How?"
"My apologies, I had forgotten, but during our final battle against ASIC, we had ran out of options and so we consulted Uranus in an old castle for help."
"Is she still there right now? I'd like to talk to her myself."
"Unfortunately, after the Gamindustri rewrite, I have not been able to locate everything, especially the old castle... but wait, that tomb right there..." Histoire pointed out towards the back of tomb that had last recorded of Uranus' reign.
"Huh, this is...?" Uzume said, taking out a small object from the centre of the tomb, and holding it in her hand.
"I recognise this, it is... a Key Fragment, it might be for that door."
"What door?"
"There's a door that I know of in the library, but I could never remember why it was there, but it it has dial with a shape that is similar to this Key Fragment," Histoire explained while she and Uzume went back to the library and they moved one of the book shelves away, revealing a door with four slots that matched the Key Fragment perfectly.
"Whoa, so there's something like this here... And even you don't know anything about it, Histoire?"
"Unfortunately no, but I should... along with the rest of what happened to Uranus' reign... perhaps the answers we seek lie beyond this door."
"All right! Leave this one to me, I've read enough for awhile now, maybe the libraries of the other nations will have the other Key Fragments, just like in the first game or somethin..."
"Oh my, you are starting to sound like Neptune now..."
"Hehe, sorry. I thought that maybe this is something that the CPU of Planeptune always did. Anyway, I'll be right back!" Uzume said, taking off in the direction of Leanbox. Uzume had began to leave, but almost crashed into Neptune, who had just returned to the basilicom.
"Whoa! Hello there Uzume! Haven't seen you around, how are you doing?" Neptune asked.
"Oh things are just great! Since big Nepsy had been back to her own dimension for a bit and I've been travelling, I decided to read up on what happened to Planeptune after I sealed myself away," Uzume responded.
"Ah... that's... great, so what did you find?"
"Hm? Well, I found out a little bit about Uranus and her reign, looks like she was successful just like you have been with Histoire, it's great!"
"I see..."
"Nepsy? You all right?"
"Huh? Oh yes, everything is fine. So what are you doing now?"
"I am heading out elsewhere, there seems to be something missing from what I was reading, so to avoid spoilers from reading a later chapter I am going to see if I can find the story from where I left off."
"That's good. Oh! I should report back to Histy before she scolds me again, I'll see you later!" Neptune finished, before rushing through to Histoire while Uzume was not at all surprised by Neptune's reaction, knowing that the current CPU must have done something embarrassing in her reign (and Uzume would bet credits that it involves pudding) that she does not want anybody to read about.
A short journey off to Leanbox and into the library was uneventful, it was quite a peaceful time after all. Uzume got to work quickly, searching through the history books and finding what she wanted. However, it was the same thing as in Planeptune: The records speak of Viridian Heart and the war with the nations and ASIC. The next book was about Vert and the peaceful demilitarisation of Leanbox and more pasture lands all around. Meanwhile, somebody had taken note of Uzume at the table and spoke up to her.
"Uzume! I didn't expect to see you here," said the voice.
"Huh? Oh, Gearsy! I didn't expect to see you here either!" Uzume responded, seeing both Nepgear and Vert walking around the library of all places.
"Oh my, looking through Leanbox's history are you?" Vert asked, noticing the historical books that Uzume had out.
"Ah yeah, wanted to find out what happened with history after I was sealed... but hey, there's something strange here..." Uzume trailed off as she explained what she had found in Planeptune and now finding the exact same thing with history being cut off at a certain point.
"I see... so ASIC was already active back then too..." Nepgear responded, first time hearing about that history of Gamindustri.
"Hm, that is strange indeed. I remember Chika did have a big book that contained more records in regards to Leanbox's history, let me go check..." Vert responded, while Uzume and Nepgear followed along. Surely enough, said book did contain the same Key Fragment that Uzume described but again, contents of Leanbox's history was missing. Still, having no real use for the Key Fragment, Vert handed it over to Uzume.
"Are you sure this is all right? This belongs to a book by somebody important to you," Uzume inquired.
"It shall be fine, I am rather curious as to why part of Leanbox's history is missing. Besides, my sister Nepgear and myself would like to know about that part of history now that you told us about all that."
"Vert... But I am not your sister, I am only over here to fulfill some quests!" Nepgear protested.
"Hahaha, you sure are popular Gearsy. Well, you guys are free to accompany me if you want, as long as it doesn't put yourself in trouble that is," Uzume said, getting ready to head for Lastation. Of course, with such an interesting case, Nepgear and Vert decided to join the party to search for the mysterious missing parts of history like some fun game... Though things seem to get rather strange when they arrived at Lastation.
The very exact same thing was in Lastation's records, the first battle with ASIC and Gamindustri from the perspective of Blue Heart, but cut off before it ended and next book was obviously about Lonely Heart Noire. Of course, this was made known to Noire and Uni as well, and soon the interest in Uzume's quest grew. Noire however, only joined because the records wrote her down as Lonely Heart Noire, to which she detests, and immediately found the oldest record book she had along with the Key Fragment. Everybody then headed to Lowee.
By now, everybody knew what to expect: Missing history, and old book having the Key Fragment, as was the pattern. Still, to have history erased from all records and even hidden from Histoire must mean somebody must have done it maliciously and trying to keep something hidden. Still, heading to the library, Blanc was already there as always, and to everybody's surprise though, Blanc was well aware of the missing history as well as the book with the Key Fragment. It would appear Blanc was already searching for the missing pieces in history as a side quest all this time. Upon hearing of the discovery of the other Key Fragments, Blanc also willingly gave her Key Fragment in hopes of uncovering the truth. At this point, Rom and Ram also wanted to tag along, to which Blanc tried to deny them, but it was no use since they were eavesdropping on earlier conversations about the history and first ASIC battle.
Finally, with all the Key Fragments in hand, a rather large party headed off to Planeptune just like anytime there was a crisis in Gamindustri, except this time there was no catastrophic event taking place, just some rather oddity that somehow drew everybody's interest. Heading back to the library, everybody crowded inside the library as Uzume placed all four Key Fragments in place, the Key Fragments lit up and the door disappeared. As everybody expectantly watched for something to happen, there was a sudden burst in light, engulfing the whole room. It was as if a sharing field has been activated, but unlike a sharing field, the location just seems to have changed, as the the environment around the party was now of a ruin, with broken pillars and rock walls around them. However, right where the door of the Key Fragment was is now a large creature of legs that resembled an ant and an upper body that was humanoid all in grayish brown.
It was a disgusting creature that was unworldly, not even Zero or Heart Dimension had such a thing, but Nepgear's N-Gear identified it as a Guard Vermin, to which Neptune would have probably made a joke about if she had been in the party. Still, with many CPU and CPU Candidates present, the Guard Vermin was no match for them all, even if it did put up great resistance. After the surprisingly long battle, the field dissolved and everybody returned to the library, and finally, Uzume reached out to the previously locked door and picked up a golden tomb with chains around it and binded in the centre with a lock.
"Damn, Four Key Fragments, a monster, and these chains all just to protect this one book. Just what the hell happened during Uranus' reign anyway?" Uzume said, holding the prize at the end of this journey.
"Somebody's trying to hide something no doubt, but what could possibly be so bad that they put all these in place...?" Blanc questioned, seeing as the gravity of the situation had changed from mere curiosity into possibly something grim.
"Well, this looks like just an ordinary lock that we can pick, but after that surprise attack, I'd say we get some rest first..." Uzume suggested, as the party got out of the cramped space of the library and back into the conference room of the basilicom to have a short respite.
Histoire and Umio were filled in by Uzume during this time, and they were interested in the contents of the hidden tomb as well, especially with what transpired inside the library with the Guard Vermin. Histoire also noticed that the golden tomb was indeed one of her tombs, and that this type of book allowed people to experience the past as if they were right there in the scene. However, Histoire still had absolutely no recollection of sealing history away in this tomb or when she did it.
Since Nepgear was used to always using screwdrivers and other equipment, breaking the lock was left to her, which was easy enough to break the lock and tear away the chains. Finally, after everybody had gathered in the conference room again, they were ready to dive into the missing part of history that was meticulously sealed away.
"Wait a second, where's Neptune?" Nepgear asked, noticing that everybody in the party as in Planeptune as usual, but Neptune had been distinctly absent this time.
"I talked to her a little while ago, she seemed bothered by the whole thing of looking into this as well as saying its going to be boring and just ran off..." Uzume explained.
"Geez, she doesn't take anything seriously these days..." Noire commented.
"Still, I don't blame her, if I wasn't sealed away I probably wouldn't have much interest in something like this either. Anyway, let's see what was so mysteriously sealed up now!" Uzume declared, slowly opening the golden tomb carefully, being wary of any further traps that might be hidden.