51 Teach Me - My Little Sister Is Only Ever Cold to Me, Yet Recently She’s Been Strangely Clingy

Chapter 51: Teach Me Is this what study sessions are supposed to be like—so much close contact? Questions crowd my mind. We were supposed to spread our textbooks and reference materials over the small foldable table I’ve been using since childhood, and study sitting next to each other. "Onee-chan, I don't get it." Ren frequently says this as she worked on her math studies, leaning her body against me, almost hugging me. Each time, my heart pounds, and I get distracted by her sudden proximity—her warmth, her scent. The numbers simply slip away from my thoughts. Still, I somehow manage to explain the problems to Ren, referencing the answers. Soon after, though: "I don't get it." She leans against me again, and it seems like the time we spend pressed together is longer than the time actually studying. "Could it be that Ren is... not good at math?" I ask Ren, who’s practically draped over me. "...Yeah. That's why I need Onee-chan to teach me, or I won’t be able to study." She says this, wrapping her arms around me. It's surprising to see Ren so overtly struggling with a subject. She used to proudly show off perfect test scores to me and Mom, and I had the impression that she was always good at everything from middle school onwards. Regardless, this is troublesome. I hadn't been making any progress with my studies for a while now. Ren was so close, my heart was beating hard, and the numbers were spilling out of my head. Desperately thinking with my head boiling, I recall an old tactic. "Okay, Ren. If you solve all the practice book problems that are in the test section, I'll give you a reward. I'll do anything you say." "Anything...?" "Yeah." In that instant, Ren, who had been practically liquefied against me, straightens her back, resuming her cool, mature demeanor. She begins solving the problems with incredible speed. I stare at her in amazement, then, determined not to be outdone, turn my attention back to my own studies. However, my concentration didn't last long. Less than an hour after suggesting the reward to Ren: "I'm done." Ren announces this and shows me a notebook filled with equations and red circled answers. "So, you weren't struggling with math, huh?" "I suddenly just got it." "That's good..." "Now, for my reward." "Uh..." I hadn’t expected Ren to finish so quickly, and I regret my careless promise. Yet alongside this regret, a touch of anticipation stirs—a trace Ren seemingly acknowledges as she softly requests: "Kiss me." "Eh?" "A kiss, please." Ren closes her eyes, as if it’s the most natural thing in the world to press our lips together. As if it were like part of our daily life, like stroking her hair or sleeping side by side. If kissing became a normal thing, I think it would be really bad. After all, I'm her big sister, and Ren is the little sister I have to protect, so I don't think it's right to just press my lips against hers randomly. It's not something a "good girl" would do, as Mom and Yuka-chan might say. Yet, this time I’m only doing it to fulfil the promise to do whatever she wants. Promises must be kept, after all. With excuses like this in my mind, I cradle Ren’s cheek in my hand. Her smooth skin meets my palm. A slight shiver passes through her. Realizing that for Ren, too, kissing is special makes me inexplicably happy. Driven by my racing heartbeat, I lean in and touch our lips together. When our lips meet, there’s a cool sensation, quite soothing. Despite its chill, the pleasure that wells up from it burns hot, and I find myself drawn into that contrast, lost within it. Ren’s soft breaths and our mingling warmth send my mind reeling. Every time our lips part, there's a lingering sense of longing. As if all these emotions want to meld together. "Teach me more." With those words from Ren, we easily repeat the act, again and again. The excuses and restraint I clung to before the kiss vanish without a trace. The math I tried to learn gets colored over by pleasure, and we devoted ourselves to studying only the sensations of each other’s lips.