Prologue

“Congratulations on your engagement. This is my gift. Your engagement present.”

With words of celebration, Richel, a friend, handed Elsia a small white box.

“Thank you.”

As soon as Elsia received the gift, she untied the ribbon and opened the box. Inside was a necklace adorned with a blue gemstone, about the size of a fingertip.

“A necklace? Why a necklace?”

‘A necklace as an engagement gift…’

Elsia tilted her head at the unusual present. It felt strange to receive something that lovers might exchange, from a friend. She and Richel had never exchanged accessories as gifts before, which made her even more curious.

“Hmm… I spent a lot of time wondering what to give you for your wedding gift. I hesitated whether to give you this or not, but I thought you might need it. Although, I’m not sure if it will be a blessing or a curse for you.”

Richel left Elsia with a meaningful comment as she tilted her head.

“A curse?”

Elsia picked up the necklace and examined it from all angles. It didn’t seem special at all. To her eyes, it was just a simple necklace with a small, round blue gem. Yet, Richel’s words and expression, which felt different from usual, made Elsia think the necklace might be more than it appeared.

‘Is there something special about it?’

Elsia looked more closely at the necklace, but the surface was smooth and the gem was perfectly round—no matter how she looked, it seemed ordinary.

“Ahahaha.”

Richel began to laugh, finding Elsia’s reaction amusing.

“Were you teasing me?”

Elsia squinted at Richel for a moment.

“I’m not teasing you. Ahaha.”

Despite denying it, Richel kept laughing.

‘She says she’s not teasing, but why is she laughing?’

Elsia felt as if Richel was teasing her, so she stared at her friend with a pouty face.

“Don’t just laugh. Tell me. Judging by your reaction, you didn’t give me the necklace without thinking… It seems like something special is hidden inside?”

Elsia grabbed Richel’s hand and pressed her to explain.

“You’re right. That is…”

After laughing for a while, Richel stopped and tried to answer, but couldn’t hold back her laughter, her lips twitching.

“Hurry up and tell me.”

“It’s…”

When Elsia urged her again, Richel’s smile faded, and she hesitated, opening and closing her mouth.

‘Just say it already…’

Richel, who had laughed so loudly, now seemed to be hesitating.

Her eyes looked anxious, and she seemed to be glancing at the maids nearby.

‘What is it that makes her so hesitant to speak…’

Richel laughed loudly not only when something was funny but also when she was embarrassed. Elsia thought Richel must be embarrassed to talk about whatever it was.

Elsia ordered the maids in the room to leave and close the door.

“Is it hard to talk in front of the maids? I’ve sent them all out, so speak comfortably.”

After confirming they were gone, Elsia spoke to Richel.

“Well… that necklace has magic imbued in it.”

As soon as the maids left, Richel spoke.

It was clearly something she didn’t want to say in front of others.

But the unexpected word from Richel made Elsia’s eyes widen.

“Magic?”

Elsia looked over the necklace again at Richel’s words.

“There’s magic in this necklace?”

Elsia was amazed and fascinated.

Magic was rumored to exist in the distant Lux continent, but in the Soloi Empire where they lived, no one knew its reality. Many dismissed the idea as a trick.

But now, magic actually existed, and it was inside the necklace right before her eyes!

“What kind of magic?”

Elsia became curious about what kind of magic was in the necklace.

Richel sighed deeply and beckoned Elsia to come closer.

She was cautious in case someone outside might overhear.

Elsia, still suspicious, moved to sit right next to Richel.

As Elsia came closer, Richel whispered in her ear.

“Have you… ever slept with a man?”

Elsia was startled by Richel’s unexpected question.

She had never spent a night with a man, and suddenly talking about it with Richel made her feel embarrassed.

Elsia couldn’t answer, only blinking and slowly shaking her head.

Richel smiled, finding Elsia’s reaction amusing, and whispered softly.

“Do you know? Even if you can’t tell from the outside, when a man and woman become intimate, there’s a form that fits well between them.”

Elsia tilted her head at something she had never heard before.

“Have you heard of ‘s*xual compatibility’?”

Elsia shook her head slightly. She had never heard of it.

“If you meet someone who fits you perfectly, even after hours together, your body feels light as a feather. And if you meet such a person, you can never forget their touch. That’s what it means to be sexually compatible.”

“No way.”

Elsia laughed at Richel’s words, thinking it was nonsense, but Richel’s serious expression made her feel it wasn’t a joke.

“So, why did you suddenly bring this up? Is it related to the gift you gave me?”

At Elsia’s question, Richel swallowed nervously and sighed before speaking.

“Yes. This is a magical necklace that tells you whether you’re sexually compatible even before you try.”

“What?”

Elsia was so shocked by Richel’s words that she stood up without thinking.

‘S*xual compatibility… That’s why she was hesitant.’

Elsia finally understood Richel’s strange behavior.

Her face grew redder, and Richel’s face also flushed.

They had been friends for over ten years, but had never had this kind of conversation, so it was only natural to feel awkward.

In the uncomfortable atmosphere, Richel started giggling again.

“We’re adults now. You have a fiancé, so I thought you might need it. It was embarrassing to bring it up, but so what? We’re adults. Aren’t you curious?”

Despite her flushed face, Richel spoke confidently, as if it was nothing.

Elsia nodded slowly, admitting Richel was right.

They weren’t girls anymore. Several years had passed since they became adults, and it was time to marry and have children, so it was natural to know these things.

But a necklace that tells you about s*xual compatibility? Elsia had never heard of such a thing.

“Is what you said really… true? Where did you get something like this to give me as a gift?”

Elsia was bewildered by the unbelievable gift.

A necklace that reveals something you can’t know from the outside… Just thinking about it was fascinating.

“It came from across the water. You know my father likes to travel, right? He met a mage by chance in Lux continent.”

“What? A mage?”

At the word ‘mage,’ Elsia was so surprised she shouted.

“Yes. I was surprised too. I didn’t think mages actually existed. But since they do, he could give you an item imbued with magic.”

“That makes sense.”

Elsia nodded, accepting Richel’s explanation.

“He happened to be studying magic related to intimacy, so he gave my father a few as gifts to try out.”

“Isn’t it a scam? Did you test it?”

Elsia was still skeptical about mages and magic.

“Of course.”

Richel nodded. Her eyes sparkled, as if all the verification was done.

Seeing her like that, it seemed the mage was real.

“How? Did you try it yourself?”

Elsia asked, feeling both embarrassed and flustered.

“I wish, but… not yet. It’s hard to find a man who fits me.”

Richel answered with a regretful expression. Apparently, it was difficult to find someone with matching s*xual compatibility.

“Then? How can you be sure the necklace works?”

“I experimented by asking people working in the mansion.”

“How did you know if they were compatible?”

“When the person who last touched the gem and their compatible partner came close, the color of the gem changed.”

“The color changes?”

“Yes. I asked couples whose gem changed and those whose didn’t, and only the couples whose gem changed were happy together, like magnets drawn to each other.”

At Richel’s words, Elsia examined the necklace again. A gem that changes color… She had never heard of or seen such a thing.

“Is that why you gave me the necklace?”

“I told you earlier. It’s a good chance to see if you’re compatible with Mars, the eldest son of the Welsley Earldom.”

“What if the color doesn’t change in front of my fiancé? Why are you giving me something like this?”

Elsia suddenly felt anxious.

If the color didn’t change in front of him, would she be able to handle the consequences? It could lead to new worries.

“That’s why I said it could be a curse. But aren’t you curious? You can find out if you’re compatible before knowing each other’s bodies!”

Honestly, it would be a lie to say she wasn’t curious.

But… but…

“Are you using me as a test subject?”

Elsia looked at Richel with suspicion.

Richel seemed flustered and started wiping her sweat with a handkerchief.

“Isn’t it better to know before experiencing disappointment?”

“Then you should try it yourself first!”

Talking with Richel, Elsia couldn’t help but laugh.

Richel kept urging Elsia to try it, even though she didn’t know herself.

But Elsia understood Richel’s feelings in giving her the gift and encouraging her to use it.

“I’ll accept the gift, but… I’ll handle the rest myself.”

“Right, whether you check with your fiancé or not, it’s your choice. Just don’t blame me if it doesn’t match! And keep this necklace a secret from others. It’s a test product before being commercialized.”

Richel earnestly requested Elsia.

“Okay. I won’t blame you no matter what happens.”

Elsia put the necklace around her neck and looked at the gem.

She couldn’t fully believe Richel’s words, but like a pebble thrown into a calm lake, the necklace seemed to stir a ripple of curiosity in her heart.