Private Biology Class

The classroom was still buzzing with the usual end-of-day chatter when Leeseo slumped down in her chair with a dramatic sigh, burying her face in her arms.

“I failed again…” she mumbled into her sleeve, voice muffled and pitiful. “Biology is actually going to kill me this time.”

Next to her, Kyujin, her sharp-tongued but kind classmate, let out a bright laugh. “Again? Girl, this is like the third time! What happened this round?”

Leeseo lifted her head, pouting cutely as she pushed her long dark hair behind her ear. “I don’t know… I tried! But between rehearsals, recordings, flights, and fan meetings… my brain just turns into mush when I open the textbook at 2 a.m. in a hotel room.”

Kyujin raised an eyebrow, smirking. “Ah right, Miss Idol is too busy living the glamorous life. Must be nice jetting around the country while the rest of us normal students actually attend class.”

Leeseo whined and lightly smacked her friend’s arm. “Yah! It’s not glamorous at all! I have extra permission from the school because of my schedule, but that doesn’t make studying any easier. I can’t even relate to normal student life anymore. While you guys are chilling at home, I’m practicing until my legs feel like jelly or trying not to fall asleep during meetings.”

She sighed again, deeper this time, resting her chin on her hand. “I feel so behind… I really don’t want to repeat this subject.”

Kyujin’s expression softened. She reached into her bag and pulled out a neatly organized notebook, sliding it across the desk. “Here. My notes for the last two units. I write everything down super detailed because I know you’ll need them later. The latest one is on human reproduction, diagrams, explanations, the whole thing. Super meticulous, even if the topic is kinda… spicy.”

Leeseo’s eyes lit up as she took the notebook. “Kyujin-ah, you’re a lifesaver! Seriously, thank you so much.” She flipped it open curiously, scanning the pages. The handwriting was clean and organized, with colorful tabs and little sticky notes. “Wow… your notes are actually really pretty. And detailed.”

She turned another page and suddenly froze, cheeks turning a soft pink.

The current chapter heading in big bold letters: Human Reproduction – Fertilization, Implantation, and Gestation.

There were detailed diagrams of reproductive organs, step-by-step explanations of the process, and even small illustrations showing sperm meeting egg. Leeseo swallowed, suddenly feeling warm.

“Umm… this is what we’re learning right now?” she asked, voice a little higher than usual.

Kyujin grinned mischievously. “Yep. Mr. Teacher is really going in depth with this unit. Good luck studying that one alone~ Don’t think too hard about the diagrams, okay?” She winked playfully.

Leeseo laughed awkwardly, trying to play it cool even as her mind wandered. “Y-yeah… I’ll just copy these tonight and try to memorize everything. Thanks again, really.”

Kyujin stood up and slung her bag over her shoulder. “No problem! Good luck with your study session. Text me if you need anything else. And hey — try not to fail again, or you’ll end up having private lessons with the teacher. He’s strict but kinda hot, right?” She giggled and waved. “See you tomorrow!”

“Kyujin!” Leeseo yelped, face burning as her friend left the classroom laughing.

Now alone, Leeseo stared down at the open notebook. The classroom was quiet except for the distant sound of students in the hallway. She tried to focus, copying the notes carefully into her own book, but her eyes kept drifting back to the detailed diagrams and descriptions.

The late afternoon sun filtered through the half-open windows of the third-floor classroom, carrying a gentle breeze that rustled the pages of Leeseo’s notebook. Outside, the lively sounds of school life still continued, groups of students laughing loudly near the sports field, the rhythmic thump of a basketball from the extracurricular club practicing, and distant chatter echoing down the hallways. It felt so normal. So peaceful. Everything Leeseo wished she could experience more often.

She sat alone at her desk near the window, Kyujin’s meticulously organized notebook open in front of her. With a heavy sigh, Leeseo flipped to the next chapter.

Female Reproduction System

Her cheeks instantly warmed. Why does it have to be this unit… of all things?

Kyujin’s notes were frighteningly detailed. Color-coded headings, neat diagrams with tiny handwritten labels, arrows pointing to every part, and even small side notes with mnemonics. Leeseo traced her finger along one of the beautifully drawn illustrations of the female reproductive system.

Wow… Kyujin really went all out, she thought, biting her lower lip. Look at how she labeled everything so clearly — ovaries, fallopian tubes, uterus, cervix… even the clitoris and vaginal canal. It’s so precise it’s almost embarrassing.

A soft breeze blew in again, cooling her flushed face. She tapped her cheek lightly with both hands, trying to snap herself out of it.

“Okay… I won’t fail again. This time I will succeed,” she whispered firmly to herself. “Fighting, Leeseo!”

But the more she read, the more her mind wandered. Kyujin had written everything in such an intimate, clinical way — describing how the uterus lining thickens in preparation for fertilization, how sperm must travel through the cervix, and the exact process of implantation.

Leeseo stared up at the ceiling, letting out a quiet “Arghhh…” as her face burned hotter. This is too much. How am I supposed to memorize this without feeling weird? It’s so… detailed. The way everything connects, how a man’s… thing… goes inside and…

She shook her head quickly, ponytail swaying, and forced her eyes back to the page. No. Focus. You’re an idol. You memorize choreography and lyrics all the time. This should be easy. Just treat it like another script.

The distant sound of students cheering outside floated in through the window as the basketball game continued. Leeseo tried to concentrate again, reading Kyujin’s neat paragraph about the female reproductive organs out loud in a soft whisper:

“‘The vagina serves as the passageway for menstrual flow, intercourse, and childbirth…’”

She immediately stopped, pressing her thighs together under the desk. Oh my god, why does this sound so…

Still, she kept going. Page after page. Copying diagrams. Repeating definitions under her breath. The breeze kept blowing gently, turning the pages whenever she lifted her hand.

Leeseo flipped the page, moving on to the next chapter.

Male Reproduction System

A small, involuntary giggle escaped her lips as she took in Kyujin’s notes. Her classmate had gone all out again.. Clean, colorful diagrams of the male anatomy, carefully labeled with arrows pointing to every part: testes, epididymis, vas deferens, prostate gland, and of course, the penis in both flaccid and erect states. There were even tiny illustrative pictures that looked almost too realistic for school notes.

“Kyujin-ah… you really drew all of this?” Leeseo whispered with a shy laugh, covering her mouth. The breeze from the window fluttered the pages again, as if teasing her.

But as she kept reading, her laughter slowly faded and her curiosity grew. Kyujin’s explanations were incredibly thorough. She described how blood flow increases during arousal, causing the penis to become erect. How the muscles contract during ejaculation. And then… the numbers.

Leeseo’s eyes widened slightly.

Average sperm count per ejaculation… 200 to 500 million sperm cells? she read silently. And the volume can be…

Her thighs pressed together under the desk again. A warm, fluttery feeling spread through her stomach. She imagined the diagrams coming to life in her mind — the way it gets hard, the way it throbs, the way it can shoot so much…

She quickly shook her head, face burning bright red now. What am I even thinking?! This is so embarrassing…

The classroom was much quieter now. Only the soft rustling of leaves outside and the occasional distant shout from the remaining students on the field remained. The golden afternoon light made everything feel a little warmer, a little more intimate.

Leeseo stared at the detailed cross-section diagram of an erect penis for a few seconds too long before catching herself. She tapped both cheeks with her palms — a little harder this time.

“Okay okay, this is just a biology lesson! Don’t get yourself stupid, dummy!” she muttered under her breath, trying to scold herself into focus. “It’s science. Just science. You need to pass this test. Come on, Leeseo.”

She took a deep breath and continued copying the notes, repeating the key terms quietly to herself.

“Erection… ejaculation… seminal fluid… sperm delivery…”

Every word made her shift uncomfortably in her seat. No matter how hard she tried to stay clinical, her young mind kept wandering into dangerous territory. The diagrams were so detailed. Kyujin had even added small notes about sensitivity and duration.

Leeseo let out another soft “Argh…” and looked up at the ceiling again, fanning her warm face with her hand. The breeze from the window felt nice against her flushed skin, but it wasn’t helping her focus.

Leeseo turned the page again, moving into the section titled “Copulation and Fertilization Process.”