Multiverse: The Daily Life of the Inventor in another world

When Venelana teleported into the workshop, the first thing she saw was her Master using Serafall's lap as a pillow, his right hand encased in a makeshift ice holder.

"What happened here?" she asked, raising an eyebrow. Why was she always late to these events?

"Master tested his gun. It was a complete success… well, it was too successful, and his hand couldn't handle the recoil," Serafall explained with a sigh, gently stroking her Master's hair.

"I see…" Venelana said, her curiosity piqued.

"You can see it for yourself in the test room," the black-haired Satan added.

Venelana, unable to resist, quickly made her way to the test room. Upon entering, she saw the destruction— the far end of the room had been completely obliterated. It was as if a massive explosion had erased everything there.

She gulped, realizing that this had been just a single shot. The weapon's power was off the charts. Now more than ever, she understood how important it was to get him on their side.

At the same time, this made her hesitant. She knew all too well how likely he was to enslave her family members, just like he had done with her son's Queen.

But that was a small price to pay in the grand scheme of things… In the end, Serafall had profited from this. Venelana could see how the Leviathan was living now. She had never seen her like this before… not fake.

'As long as my family doesn't suffer… It doesn't matter,' Venelana thought as she turned and left the test room.

Returning to the workshop, she walked towards the sitting area. By this point, the workshop had expanded into one massive room. There was Marcus's main design and PC area, a large empty space that Venelana believed would be used for his creations, a summoning/ritual room on the left, a testing room on the right, and at the back, the entry lobby with a small kitchen and bathroom.

With a size larger than his entire house territory, she couldn't help but wonder if the Diamond Core Heart had handled the explosion properly. Otherwise, people might be calling the authorities to find out what happened.

"That is quite the destruction. Is it truly just a single shot?" Venelana asked as she walked over and took a seat opposite Serafall and her Master.

"It is. I can safely classify it as a High-Class Sacred Gear, or even a lower-tier Longinus Gear," Leviathan said proudly.

Cold sweat ran down Venelana's spine. Well, it's now or never. This is the perfect opportunity to offer him a chance to visit Kuoh and test the gun in a more... live setting.

"I see… still, testing it inside isn't recommended, as the area above is church-controlled. You need to test it properly," the brown-haired devil lady said, starting to outline her idea.

"What do you suggest? Devil-controlled land?" Marcus asked.

"Indeed. An area directly under the control of the Gremory and Sitri families. There, you could easily test your guns," Venelana offered, glancing at Serafall with a subtle motion to help her with this proposal.

"...If you want something, Venelana, just ask directly. There's no need for you to speak in circles," Marcus said with a sigh, not even bothering to open his eyes. He preferred to relax in Serafall's lap.

"Very well. Both my daughter and Serafall's younger sister will be moving to Kuoh starting next semester. The city doesn't have a proper barrier system, and the area is frequently known for having stray devils. My suggestion is that you could set up a system and test your guns there," Venelana said with a sigh. She didn't like speaking so bluntly, but it felt necessary. The devils didn't have a barrier system like Marcus's, and while they could set one up, the Shinto faction would investigate, as their barriers emitted demonic essence.

The Shinto Gods didn't like large amounts of concentrated demonic energy.

This left them with an alternative: an outsider, a third party, who could carry it out.

Both of the devil ladies waited for Marcus to think it over. The teenage inventor didn't want to go anywhere near Kuoh, but he knew there was a Longinus-gear there that didn't belong to any faction, and he understood that Kuoh was the center of many events. Having something stationed there to collect data would be a goldmine.

And, lastly, both Serafall and Venelana were connected to this. That meant he could earn some brownie points with both of them—and gain a lot in return.

"Very well. There are conditions for this, though," he said after some time.

Both Serafall and Venelana sighed in relief.

"Like?"

"I'll be deploying a much weaker version of the Diamond Core Heart, and both of them will need to sign a Devil Contract with me," he said simply.

"...What do these contracts entail?" The brown-haired devil lady asked, a little fearful. She had no idea what kind of contracts he was talking about. Were they modern ones or ancient ones? They were vastly different.

"Nothing for you two to worry about. I have no interest in your daughter or Sera's younger sister. I prefer a much more powerful devil or someone uniquely useful. So, all I'm going to ask them is a confidentiality agreement. In other words, they'll be 'testing' my invention and sending reports on how it's working. Of course, all of that will be under wraps because if they disclose anything, it will affect their reputation as devils."

Both Serafall and Venelana nodded, satisfied. They were a bit annoyed that Marcus didn't see their sister and baby daughter as "unique" or "valuable," but they were glad he would be helping them.

"Easy enough. It sounds like regular devil business. They've been doing this for years," Serafall said.

"Yes, and client confidentiality is something they're taught from an early age," Venelana added.

"Right. Good to hear. Still, I won't be going so soon. I still need to make preparations. My guns need adjustments. The force of each shot needs to be manageable, and the cartridge has to be finished," Marcus said, slightly lifting his right hand. It was still shaking, but it was progress.

"I don't think you should be doing anything today. But think on the bright side! I can pamper you the entire time!" Serafall said cheerfully. Now she had a proper reason to pamper him! Maybe she should show him how much she appreciated the fact that he was helping her little sister.

Marcus simply sighed, settling further into her lap.

"Very well," he said, closing his eyes. Time for a nap.

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