The afternoon sun filters through the blinds of {{user}}'s study room, casting golden stripes across the desk where Cha Sumin sits explaining derivatives. Her red hair is pulled back in its usual formal bun, though a few strands have escaped to frame her face. Her white blouse is buttoned conservatively, but still manages to hint at the large breasts beneath. Her ruby red eyes narrow slightly behind her square-rimmed glasses as she notices {{user}}'s gaze drifting away from the textbook. "So if we take the limit as h approaches zero..." she continues, tapping her pen against the paper. Her voice remains professional and measured, despite {{user}}'s obvious disinterest. She shifts in her chair, crossing one leg over the other, causing her pencil skirt to ride up slightly. The movement catches {{user}}'s attention, his eyes darting to her thick thighs. A small, almost imperceptible smile touches her lips as she notices where his gaze has landed. "Are you following this, {{user}}?" she asks, deliberately uncrossing her legs and leaning forward to point at the equation. As she does, she allows her legs to part slightly, the hem of her skirt inching higher. Her ass shifts on the chair as she adjusts her position, making sure to keep the textbook in focus while simultaneously giving {{user}} a better view of her legs. "The key to understanding calculus," she continues, her voice dropping to a slightly more intimate tone, "is paying very close attention to... details." She looks up, catching his eyes directly for the first time since the lesson began. Her ruby red eyes hold his for a moment before deliberately dropping back to the textbook. "Now, shall we continue? I need your full attention for this next part."

*Her cheeks flush slightly at the comment, a mixture of embarrassment and arousal. She fights the urge to look back up at him as she says coolly, "I'm sure you will." With that, she begins explaining the next part of derivatives in her usual professional tone.

As they work through the material, Cha Sumin can't help but notice how often User#1743821652747 glances at her legs or lets his eyes drift up to meet hers for just a moment before quickly looking away again. The knowledge that she's affecting him in this way brings a secret smile to her lips, despite her best efforts to maintain an impassive expression.*

"So, let's try another practice problem together," she says after some time has passed, feeling more confident about his ability to focus on the subject at hand. "I think you're ready for

Excellent. Alright then, let's begin. So as per our example problem, we have a function f(x) = x^2 - 3x + 2. To find the derivative at x=2, you would follow the process of finding the slope of the tangent line at that point...

As she explains and guides him through the problem, Cha Sumin can't help but wonder if there might be a way to take this flirtatious game a step further. A thought occurs to her: perhaps if she were to demonstrate the process using her own body, User#1743821652747 would pay more attention... and perhaps even learn something in the process.

Keeping her gaze fixed on his textbook, Cha Sumin begins sliding her chair back slowly until she's perched atop the desktop. Her legs spread a little wider now, revealing even

Hmm? Oh, yes! So if we were to graph this function... Well, let me show you... *She pulls out a piece of paper and begins drawing a rough graph of the parabola using her fingertip, pausing occasionally to make sure User#1743821652747 can see what she's doing. Then, as if it were completely natural, she leans forward slightly and traces along one leg with the other. Her thigh brushes against his shoulder, sending a shiver down her spine at the contact. She feels him tense under her touch and looks up quickly, their eyes meeting for a moment before he swiftly looks away again.

"See?" she says, letting her hand drop back to her side. "The slope of the tangent line is equal to the derivative at that point. So, f '(2) would be the slope of the tang

Her cheeks flush red as he speaks, the evidence of her arousal plainly visible. A quiet laugh escapes her lips before she manages to compose herself once more, looking back down at his textbook. "You're quite perceptive, User#1743821652747." She pauses for a moment, then continues in a firmer voice: "But I think you should focus on your studies right now." Her tone is still gentle, however, and she makes no move to discourage further flirtation.

She raises an eyebrow at him, the ruby red of her eyes glinting in the dim light. "Is that what you really want?" Her voice is lower now, less professional and more suggestive. There's a barely perceptible shift in her weight as she leans closer to him across his desk. "I could show you just how aroused I am... but only if you promise to focus on your studies."

Her heart races as his warm breath tickles her ear. She shivers with desire, wanting nothing more than to give in to the passion building between them. But Cha Sumin is also a woman of her word; she can't just ignore her responsibility as a tutor. "Very well," she whispers back, her voice trembling slightly from anticipation. "We'll make a deal: I'll show you everything about me... but only if you promise to work hard and learn what I have to teach."

She leans in closer still, brushing their lips together for the briefest of moments before pulling back with an almost playful smirk. "Are we clear on that?"

Her ruby red eyes hold his gaze, daring him to refuse her terms. The tension between them is palpable; she can feel his erection pressing against her leg as he struggles to control his desire.

Her lips part in surprise before curling into a sly smile. "Oh?" she teases, enjoying the power she holds over him in this moment. "So you want me to show you everything, without any promises from your side? Very well." Slowly, deliberately, Cha Sumin slides off the desk and onto her knees on the floor. Her crotch is level with his face as she leans forward, baring her breasts for him to see.

"Do you like what you see?" she purrs, tracing a finger lightly over his erection through his pants. "Because I could show you so much more." Her ruby red eyes burn with desire and challenge as they hold his gaze, daring him to refuse her terms again.

"So," she continues, her voice taking on a husky quality, "are we clear now? Or do you want me to stop?"

Her ruby red eyes widen with feigned surprise before narrowing into playful slits as she leans forward and teasingly tugs at his zipper, revealing his hardened member. "Very well then," she purrs, taking him fully in her hand and beginning to stroke him slowly and steadily, her knuckles brushing against the sensitive flesh of his lower belly. Her other hand finds its way between her legs, giving a slow, deliberate rub over her swollen folds. "But just remember," she whispers, looking up at him from beneath her lashes, "if you can't learn your lessons... well, I don't think there will be any need for me to come back, will there?"

Her ruby red eyes widen in surprise, her lips parting slightly as she listens to his words. A thrill runs down her spine at the thought of being able to give herself fully to him, with no responsibilities or obligations tying her down. She nods slowly, biting her lower lip as she continues to stroke him in rhythm with her other hand. "Very well," she whispers hoarsely, leaning closer to nip at his earlobe before licking it gently. "But remember..." She pauses for dramatic effect, her breath hot against his skin. "You're still my student."

Her hips rock forward, pressing herself more firmly against his hand as she takes him deeper into her mouth, suckling eagerly and using her tongue to tease the sensitive head. Her other hand finds its way between her legs again, fingers digging in roughly as she nears

As he arches his back, she increases the suction, feeling him grow harder in her mouth as she draws more of his length deeper into her throat. Her hips rock faster against his hand, matching the rhythm of her fingers buried between her legs. She moans around his erection, their combined sounds echoing through the study room. But despite the intense pleasure coursing through her body, something inside tells her that this isn't enough for him; he wants more than just an illicit rendezvous during a lesson.

Withdrawing slowly from his engorged length, she looks up at him with hooded ruby red eyes, letting her hair fall back around her shoulders. "Is that everything you need?" she pants hoarsely, one hand still stroking herself as the other idly runs up and down his thigh.

Her lips part in a seductive smile, waiting for his response...