The Betrayer's Calculated Theft

Yumin slowly flipped through the supplementary materials, meticulously reviewing every detail of Choi Junyoung's personal information. As he had anticipated, there was a section on the love triangle involving himself, Seo Soyoung, and Choi Junyoung. But the contents were nothing like what Yumin had expected.

What surprised Yumin first was that Junyoung had a history of seducing his acquaintances' girlfriends—not just once or twice. Even more shocking was how Junyoung and Soyoung had gotten together. It wasn't the clichéd story of the three of them hanging out often, spending time together, and naturally developing feelings that led to Soyoung cheating with Junyoung.

From the start, Junyoung had been drawn to the fact that Soyoung was the girlfriend of his close younger friend Yumin. He approached her deliberately to steal her away from Yumin. And it wasn't some impulsive flow of events—it was highly systematic.

He positioned himself to Yumin as a close older brother figure who could offer advice. To Soyoung, he presented himself as the acquaintance who knew her boyfriend Yumin best. As Yumin read on, memories from that time flooded back vividly.

Of course, if there had been no gaps at all in Yumin and Soyoung's relationship, Junyoung couldn't have wedged his way in. But even those gaps had been created by Junyoung himself.

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"Yumin-ah. How's it going with Soyoung these days?"

Junyoung asked casually while getting coffee from the vending machine with Yumin, noticing his somewhat gloomy expression.

"Well... Junyoung hyung..."

"What's up? Something not going well? What's there to hesitate about between us? Just spill it all out."

"It feels like... it's not going well. She seems dissatisfied with something, but I don't know what it is..."

Yumin had noticed Soyoung's dissatisfaction, but he couldn't pinpoint the exact reason. That made it all the more frustrating.

"I see. Want me to check it out for you?"

"Huh? Then she'll find out I told you about ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠this, right?"

"You think I'd be that stupid? I'll ask her subtly so she doesn't catch on."

"Junyoung hyung, would you really? Thank you so much."

"What are you talking about... between us..."

The next day, Junyoung made time separately to meet Soyoung—carefully choosing a time when Yumin wasn't around.

"Soyoung-ah. How's it with Yumin oppa lately?"

"Same as always. What... I'm getting along fine with Yumin oppa."

"You seem a bit dissatisfied, though?"

"Nah... nothing like that..."

"Just be honest. It hurts to watch from the sidelines. You know how close I am with you and Yumin, right? You two are like my favorite little siblings."

"...Yeah."

"I just want to see you two get even closer."

In Soyoung's mind, Junyoung had always been so good to both her and Yumin. Yumin especially saw him like a real brother. With Junyoung going this far, Soyoung hesitated over whether to share the worries she'd buried deep inside.

But she was concerned—could she really discuss this with her boyfriend's older brother figure, even if they were close? Her current dilemma was about the intimate side of man-woman relationships.

Soyoung was still a virgin, but she had a strong interest in sex. She wanted to take that next step with her boyfriend Yumin. But Yumin was so oblivious in that area that, with some exaggeration, he wouldn't even touch the tip of her finger. It frustrated her to no end.

"It's... embarrassing to tell you, Junyoung oppa..."

"What's there to be embarrassed about between us? It's because you two aren't having good sex, right?"

"S-sex... don't say it so bluntly..."

"Why be shy about it? Couples do it all the time, don't they? These days, even if they like each other, if the sex isn't compatible, they break ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠up."

"R-really?"

"Of course. So you're worried because the sex isn't going well?"

"Junyoung oppa... how did you know?"

"You're not the only ones. Half the worries young couples like you have are about sex. So don't be embarrassed—just tell me. ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠Is that why it's not working out?"

Hearing that everyone had these issues eased Soyoung's mind. She decided to be honest with Junyoung.

"It's not that it doesn't work... we haven't even tried..."

"I see. That's how it is..."

"......"

"So you're still a virgin, Soyoung-ah?"

"...V-virgin... mm..."

"Just be straight with me. What would I do to you, like a little sister? I need the full picture to give solid advice."

"Yeah... I am a virgin..."

"And you want to do it with Yumin, right?"

"......Yes."

"Got it. I'll keep this secret and quietly check Yumin's thoughts."

"...Yes. Thank you, Junyoung oppa."

A few days later, Junyoung arranged another meeting with Yumin and relayed Soyoung's thoughts. But it was heavily edited by Junyoung—actually twisted 180 degrees.

"Yumin-ah, I talked to Soyoung..."

"Yes, Junyoung hyung. What did she say?"

"You've been getting close with Suji sunbae lately, right?"

"Huh? She's just taking a bit of interest because I'm working hard. Not close enough to call it that."

"Yeah, I know that of course. But Soyoung seems to have misunderstood a little."

"Misunderstood...?"

"She likes chaste guys. Men who aren't swept away by desire and value her. Her ideal type is someone who can keep pure until marriage. She got jealous seeing you close with Suji sunbae."

"No, really, Suji sunbae and I have nothing going on. And I treasure Soyoung so much... I haven't even touched her fingertip until now..."

"Good job. Keep holding firm like that. Her misunderstanding will clear up soon."

"Yes. Thanks, Junyoung hyung."

Junyoung also set up a one-on-one with Soyoung and told her Yumin's "thoughts." Of course, rewritten by him again.

"Soyoung-ah. Yumin's ideal type is a woman who can lead him. Yeah... like Suji sunbae..."

"Suji... sunbae?"

"Yeah. Didn't you notice? How Yumin and Suji sunbae have been getting close lately."

"Come to think of it... it wasn't just senior-junior friendliness?"

"Not. Yet."

Junyoung deliberately emphasized "yet."

And hearing that, Soyoung started to get anxious bit by bit.

"I told him his ideal is a woman who leads him, right?"

"...Yes."

"Leading includes sex too. Actually, Yumin's still a virgin and doesn't know how to handle women."

"...Really?"

"Yeah. But Suji sunbae's dated a bunch and has a bold personality, right? If she gets closer to Yumin, what do you think happens?"

"......What?"

"Suji sunbae would take the lead with sex-inexperienced Yumin. I'm worried he'll get eaten up by her."

"E-eaten...? Then what should ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠I do?"

"How about you actively seduce Yumin?"

"...Me? Can I even do that?"

Soyoung's face turned bright red. She'd gotten swept up in the mood, but it was mortifying.

Junyoung found her adorable. Inexperienced, but more interested in that stuff than anyone. Women like her had low hurdles.

But Junyoung paused a beat. They'd crossed 80%, but to seal it, he needed to make her more desperate.

"Just try once. You okay with losing Yumin to Suji sunbae like this?"

"No. I'll try..."

"Good thinking."

A few days later, Junyoung met Soyoung again. He'd already checked with Yumin, but this was to advance things a bit.

"Soyoung-ah. How'd it go with Yumin yesterday?"

"It... didn't go well."

"How so?"

Yesterday, Soyoung had mustered her courage and seduced Yumin physically. But Yumin, misled by Junyoung's words about her tastes, rejected it.

Unaware of that, Soyoung wondered: Was Yumin not interested in her body? Or was he really falling for Suji? Her mind grew chaotic.

"I see."

"I tried seducing Yumin oppa... but with no experience, I didn't know how..."

"Yeah, makes sense. That's why it failed."

"Junyoung oppa, what should I do?"

Now, Junyoung was all Soyoung could rely on. With her last resort—physical seduction—failing, no ideas came to her.

"Want to practice with me?"

"Huh? Practice?"

"Yeah, practice. Yumin wants a woman who leads even in sex. But you said you lack experience, so you couldn't seduce him properly."

"Yes... that's right."

"Exactly. How can you lead if it's your first time? So practice with me before doing it properly with Yumin."

"Even so..."

"If you act like this, you two will never do it. Or worse, Suji sunbae might steal him first. That okay?"

"No... not that..."

Seeing Soyoung's eyes wander in hesitation, Junyoung knew she was almost hooked. Just a little more push.

"Just practice. No kissing, no penetration. Just atmosphere-building."

"No kissing, no... insertion...? Really?"

"Of course. Why would I lie to you? Do I look like the type to scheme with my close little sister and Yumin's girlfriend?"

"...No."

"Light practice. Shall we go to my place?"

"......Yes."

Yumin and Soyoung's relationship stayed in a stalemate. It teetered on a tightrope, balanced by Junyoung's mediation. Meanwhile, Junyoung and Soyoung's encounters continued. Soon, Soyoung felt no awkwardness stripping naked in front of him, receiving caresses from him, or caressing him.

----------

After reading all of Choi Junyoung's personal info, Yumin deeply regretted wanting it in the first place. For him, those events were almost forgotten. If he hadn't known, they might have faded into memory entirely.

But now he knew—not just reliving memories, but uncovering the hidden truth.

Yumin truly felt that ignorance is bliss. He couldn't bury it now. Another name was etched onto his blacklist.

----------

Yumin wasn't thrilled about Nam Sangmi as his partner for the first mission, but there was no choice. More than anything, he couldn't skip the first one.

He entered the mission room and undressed. Sangmi began stripping beside him.

Today, the way she looked at Yumin was markedly different from usual. Normally, when paired with him, she'd gaze with eyes full of expectation for hot sex. But now, mixed with that heat was a hint of fear.

Probably from the previous mission's intense anal fisting by Yumin—the pain and pleasure etched into her body simultaneously.

Missions usually gave two goals without priority—achieving either order led to success. But when priority was specified like this, the sequence had to be followed exactly.

That was why Yumin hadn't swapped Sangmi for another woman. This mission seemed straightforward at first glance, but the order made it deadly.

Insert into unprepared anus, ejaculate, then immediately into the vagina with the same penis. Yumin couldn't subject his female companions to such a hygiene nightmare.

Even Suji, an anal sex enthusiast, wouldn't want this kind.