Theory#1: S-FIT did not explode.
In Fleeting Memories, Part 5, it is stated that there are no survivors. However, on the wiki fandom, it is stated that Asimov was experimented on at S-FIT when he was a boy. Therefore, this means Asimov is a survivor and the building may not have been destroyed. In the Nova's Memories audio drama, it was stated by a scientist that they lost "good scientists and priceless research" that day. But in ASG3, Kirin read an excerpt from the file which stated "In the near future, Adepts will wipe out humanity". So, Sumeragi may not have done as good a job covering everything up as they thought.
While Dr. Kamizono was preparing his tools, neither him or his assistant thought it necessary to monitor Takefutsu. Not while he was all chained up with the Septima sealing stones nearby. And especially not with the prototyped glasses carrying the same effect as the stones. However, they couldn't have possibly made a bigger mistake.
When approached with the scalpel, Takefutsu grew violent. And, by some miracle, managed to shake the glasses off his face. He used Astrasphere to stun both scientists and break the chains restraining him. Once granted free movement, the experimental Azure Striker overrode the door lock while attempts were made to stop him.
After freeing himself from the room, the boy continued forward. A containment breach was declared throughout the floor as attempts were made to stop the escapee. With laser guns, rocket launchers, even grenades. All of which were no match for the Flashfield.
"Damn it, we lost him. The higher-ups certainly won't be taking this lightly." Dr. Kamizono lamented.
"Should we leave now sir?" His assistant wondered.
"No, they'll know he escaped while under our watch. I was the only one assigned to him after all." Dr. Kamizono denied.
"What will we tell them? They may believe the truth to be rather far fetched." The assistant worried.
"I'll handle it, you don't need to worry about a thing. I'm your superior after all, so the blame will go to me." Dr. Kamizono assured.
They certainly heard a lot of backlash regarding the escape. One comment was made that "It would have been better hearing that the building erupted in flames.".
Some years down the line, it was decided to start Project Gunvolt back up again. After running tests on a number of subjects, one popped up with what appeared to be a promising match. Subject 77: Nova Tsukuyomi.
"If this is true, then he has a better chance of obtaining the Azure Striker than Takefutsu." The second scientist gasped.
"There should still be remnants of the Azure Striker Septimosome in the Stratacombs. I'll request them to be sent up now. It should take five days to a week for the sample to arrive." The first scientist remembered.
"We just have to hope it doesn't turn into another S-FIT." The second scientist prayed.
"Isn't that when the first artificial Azure Striker caused the building to ignite?" The first scientist queried.
"It is. We should prepare some safety measures while we wait, just in case." The second scientist advised.
An electromagnetic barrier was put in place to prevent the lightning from injuring the scientists in the control room. Just like they feared, this test of the Azure Striker was a failure as well. The Azure Striker went out of control while Nova was testing it. When he went to unleash Astrasphere, the power was too much for his small body. It caused him to experience similar symptoms to electrocution. He was spasming, and received 2nd degree burns on his arms, legs and face. Nova was required to wear bandages for three weeks following the testing.
"I don't understand, we took all the right measurements. Everything was taken into accord, so why didn't it work?" The second scientist snarled.
"It seems the test results pointed us towards failure once again." The first scientist supposed.
"Maybe not. The boy with the blond hair, he may be able to point us toward hope." The second scientist supposed.
Decades later any remnants of Project Gunvolt were either forgotten or lost to time. One day, while bored out of her mind, Kirin decided to do some snooping in Sumeragi's files.
"Hm, what's this? "Septima Research Project"? Last updated, fifty years ago? Well, it looks intersting enough." Kirin noticed.
While scrolling through it, Kirin noticed something Gunvolt mentioned to her. The fluffy Primal Dragon was currently taking a nap on a large sized dog bed.
"I wouldn't do that if I were you." Lumen advised.
"Come on, this is GV we're talking about here. He wouldn't hurt a fly unless he had to. And besides, I can easily protect myself with my Radiant Fetters." Kirin assured as she poked Gunvolt a few times in his back.
His head and ears popped up as he looked around for whatever woke him up. He turned around and groggily eyed Kirin, identifying her as the source of his nap disturbance.
"Is there something you needed?" Gunvolt yawned as he stretched.
"I was snooping through some of Sumeragi's old files just now. And I found one that mentioned Project Gunvolt. That was the project you were a part of right?" Kirin answered.
"Yeah, where did you find it?" Gunvolt confirmed.
"In the Septima technology section under the subheading research. Get this, one of the lead researchers of their Septima Research Project said "In the near future, Adepts will wipe out humanity."." Kirin declared.
"Now that I think about it, a human I once fought told me that. He had this green haired robot with him. But I just can't seem to remember his name." Gunvolt remembered.
"His name was Copen. During the fight with Moebius, I got separated into an alternate world. One that supposedly was centuries ahead of our own. He was there too, as some sort of android. He was certainly as annoying to deal with as the ones Sumeragi makes that's for sure." Kirin remarked.
"He told me his father worked for Sumeragi. And if I'm not mistaken, Copen shared the exact same quote too." Gunvolt added.
"Did you ever meet him?" Kirin asked.
Gunvolt shook his head.
"The scientists that experimented on me didn't talk unless they needed to share information or it was necessary." Gunvolt stated.
"I wonder what happened to him and Copen." Kirin pondered.
One thing was for certain, nobody was going to be finding that out anytime soon.