Each time they offered blood, they would be trapped in illusions, and only those who could break free from all of them could inherit.

Breaking free from illusions seemed difficult, but it might be better than Caligo’s succession…

Perhaps she thought this way because she was biased.

Considering it happened multiple times and they described feeling their humanity erode during the process of breaking the illusions, that side didn’t seem easy either.

“Ah, this is surprisingly tricky, huh?”

“Yeah. How to control it is one thing, but where to inscribe is another problem…”

The central medium jewel was also an issue. Erenhorn’s attributes didn’t match well with black diamonds.

Consequently, they had to test compatibility with other jewels first.

Fortunately, since the ducal family owned gem mines, this was manageable—otherwise, the testing alone would have cost several houses’ worth.

After all sorts of tests, they concluded… that pink diamonds were the most compatible with Erenhorn’s attributes. This wasn’t particularly good news.

The Aberdeen family’s main mines were ruby mines, and pink diamonds weren’t from dedicated mines but were occasionally found like variants, making them hard to obtain.

Especially since they needed large carats to inscribe Arlesian and use as control mediums, large-carat pink diamonds were even harder to find.

“A ruby’s compatibility isn’t too bad either…”

“Yes. But it’s no match for pink diamonds.”

“We can’t proceed further with current information… We’ll need to ask him to come again.”

“Ah, that bastard is annoying…”

Despite being a Guardian Spirit himself, Yuri disliked all Guardian Spirits.

Though they hadn’t seen him meet Rosedale’s Canis or Francis’s Halcon, at this rate, he would probably dislike them too.

‘But Caligo seems to dislike Yuri and Erenhorn too…’

At this point, she wondered if Guardian Spirits naturally disliked each other.

“Can’t be helped.”

Though sighing, he eventually agreed.

Instead, he warned Saena to tell Duke Aberdeen to keep that bastard in check while he was there.

“Okay. Got it.”

She didn’t want to get licked(?) unnecessarily either…

Saena sent a letter to Duke Aberdeen requesting a visit when convenient for additional research questions, then concluded the research.

* * *

Then one day,

A pink diamond theft occurred at a count’s residence.

The unusual incident caused a stir throughout the imperial capital.

First, because it happened at a high-ranking noble house known for it’s good security.

Second, because the stolen item was quite a famous jewel. It was an heirloom necklace passed down in a count’s family, and the countess loved wearing it at important family events to attract others’ envy.

Finally, according to the countess’s testimony, the theft process was rather unique.

There had been a party at the count’s residence the previous night, and she kept feeling an ominous gaze. The uneasy countess headed to the third floor early to return the necklace to the safe. But suddenly, an incredibly handsome man appeared in the third-floor corridor, made her mind hazy, and stole the necklace.

People focused on the fact that the necklace thief was handsome.

“How handsome must he be to make someone’s mind go hazy?”

“Right? A thief using his face as a weapon is a first.”

“If there’s such a thief, I’d like to see him too!”

The countess cried saying the thief must have done something to her, and her crying turned to wailing when the count became suspicious of her.

In truth, he thought his wife might have brought in a man, done something improper, lost the necklace, and then made up this implausible excuse out of fear of the consequences.

The incident was so absurd that gossipmongers eagerly developed various theories, and some worried with both curiosity and fear about what they would do if this incredibly handsome thief appeared at their house.

“……”

“……”

And now that talked-about pink diamond necklace was right in front of Saena.

—Purrrr!

More precisely, it was hanging from Erenhorn’s mouth as he purred, seemingly urging her to take it.

So who was the master thief… the handsome man…?

“Haah… I’m sorry, Madam…”

And who was the most pitiful person…

The countess who lost her necklace? The count who came to doubt his wife? Or Duke Aberdeen who stood before them now, hanging his head?

“Hmm… Why are you presenting this to me?”

“He seems to have kept in mind what you said before about needing a large pink diamond.”

“Why would he keep that in mind…?”

For research to control Guardian Spirits, why would Erenhorn, a Guardian Spirit himself, welcome it and even gather (actually steal) research materials to offer?

Was it because Erenhorn was an unusual Guardian Spirit in many ways? Or was there another reason?

“I don’t really know the reason either…”

Even Duke Aberdeen didn’t know the reason, but having to clean up after this incident seemed to be driving him crazy.

—He seems to think this research is about ‘humanizing Guardian Spirits’?

At that moment, Yuri, who had deactivated his manifestation to avoid Duke Aberdeen’s eyes, spoke.

“Hmm?”

Though she actually wanted to ask ‘Hmm? Humanization research? Why on earth?’, she could only voice a brief question in front of Duke Aberdeen.

But Yuri understood immediately.

—The other day when that bastard saw my human form, he was absolutely thrilled.

“……”

Caligo was like that too, and now Erenhorn… Why were they like this? Did they want to become human? But why?

“Anyway, we can’t use this necklace.”

—Purrrrrr!

Erenhorn responded with a dissatisfied purr.

“…Will you give it to me?”

Thinking she should secure the necklace first, Saena held out her hand, but Erenhorn purred like he’s refusing to give it up without hearing the reason.

Earlier he had been eager for her to take it, but now, look at that distrustful gaze.

“Sigh… You bastard!”

Finally, only after Duke Aberdeen’s uppercut did the necklace come free from Erenhorn’s mouth.

Worried there might be damage, Saena carefully examined the jewel, but fortunately, being the famously hard diamond, it remained brilliant. However, the weaker platinum of the necklace showed clear teeth marks.

“…This part will need some repair.”

“Yes…”

Being a Guardian Spirit’s master wasn’t something glamorous after all…

Why did being Erenhorn’s master mean having to endure such shame every time…

Saena wanted to erase even her past self who had once considered Erenhorn her favorite Guardian Spirit.

“First, there was a reason I asked you to come today…”

Of course, it wasn’t about humanization.

Both Saena and Lucas knew this. Though Erenhorn seemed unaware.

“Um, could I know the exact content of the covenant text you mentioned is read during Erenhorn’s succession? Including the precise spelling?”

“Pardon? Do you need that?”

Though she had mentioned before it might be necessary, it seems he hadn’t really thought it would be.

Since adapting Caligo’s separation method had failed, they had no choice but to analyze the Aberdeen family’s covenant and power activation method separately to find a solution.

“Yes. If there’s anything inscribed on the covenant stone besides the covenant text, I think we’ll need that content too, but I’m not sure if that’s possible.”

“Hmm…”

Duke Aberdeen seemed troubled, holding his chin in thought.

Perhaps it was too sensitive to reveal to outsiders.

“If it’s a family secret… or if it’s difficult to share, you can refuse.”

“Then must we continue living like this?”

“…I’ll think about other methods too. It will take longer, and the success rate will be lower.”

Having developed an interest in jewel crafting related to Guardian Spirits, she would continue researching steadily, so even if it took time, results might come.

But she couldn’t guarantee there would definitely be results, nor could she say when.

Though they could try having Yuri befriend Erenhorn to extract(?) information about control methods, this felt too much like mining for information, so it didn’t appeal to her either.

“No. I think it’s fine to tell you, Madam. Besides, knowing the method doesn’t mean everyone can succeed in the succession.”

“Ah, is that so?”

“However, as I mentioned before, please don’t record it, and don’t use it for purposes other than research.”

“Yes. Of course.”

“And… would it be alright if you came to Aberdeen territory to see the covenant stone?”

Because it’s not something that can be easily moved…

Duke Aberdeen carefully asked, likely aware of how Duke Kramer would growl furiously if Saena were to go to Aberdeen territory.

“Hmm…”

If the covenant stone was fixed somewhere, that would make sense.

“Is there anything inscribed on it?”

“Yes. Though I’ve never seriously examined what it is, something is definitely inscribed there.”

Then it seems they would need to see it…

“Then I’ll first look at the covenant text’s contents and request that later.”

She also inquired about several other pieces of information she had organized in advance due to necessity.

After finishing their business and returning, she later heard that Duke Aberdeen had given enormous compensation to the owner of the pink diamond necklace.

She heard that the compensation included several sets of jewels worthy of becoming new family heirlooms, so they gladly sold the pink diamond necklace.

Of course, that pink diamond returned to Saena for research purposes.

* * *

Several months passed.

To state the conclusion first, the research went through several failures.

The most recent achievement showed rather unique results, but it was still a failure.

“…I’m sorry. I’ll research it again.”

Research rarely succeeds immediately.

Isn’t it through failures and mistakes, repeatedly fixing errors, that one moves toward success?

However, they weren’t given the chance to readjust the failure.

“No. I’m quite satisfied with the results!”

Duke Aberdeen rejected further research.

—Purr!

Erenhorn also seemed satisfied, bouncing around.

Why on earth…?

Saena felt confused, unable to understand.

“But this has nothing to do with control… are you sure it’s okay?”

Duke Aberdeen held up the pink diamond densely inscribed with Arlesian and smiled brightly.

“Since he ultimately can’t interfere when I’m on dates, it’s fine!”

“……”

In truth, she thought this research had come close to success, so she called Duke Aberdeen to try infusing his power.

But when he actually infused power, the result differed from expectations. It was clearly a failure without need for further examination.

However, after seeing the results, Duke Aberdeen said he wanted to try a few more tests and asked to borrow the pink diamond briefly.

Then he returned and made such statements.

Surprisingly, both the duke and the Guardian Spirit were very satisfied with the current failed product.

“He’s just invisible, not actually gone, you know?”

Why did he say Erenhorn couldn’t interfere? Wouldn’t it be an even greater disaster if he licked while invisible!

While Duke Aberdeen had borrowed the pink diamond, Saena analyzed the factors behind the failure.

She determined it was a side effect from not fully understanding Erenhorn’s abilities while arranging the inscribed seals.

That side effect was ‘invisibility’.

Considering that part of Erenhorn’s abilities involved illusions and visions, she had designed the control seals to handle this aspect too, but for some reason, it created a conflict zone that caused unexpected strange effects.