Why is reading the Kotone childhood arc of Final Subjugation Target If 2 making me nostalgic when I've never been a Japanese elementary school girl?

>“Haa…”
>The kiss in the morning had been so sudden and brief that it hadn’t felt real. But this… This was different. The sensations, the textures, were vivid. I felt something soft and fleshy against my lips. I tried to push Euru away, but my arms wouldn’t move.
>I had no choice but to accept it… A wave of dizziness washed over me, and my eyes closed involuntarily.
>“Get off of her.”
>Euru’s lips left mine, and I snapped back to reality. I opened my eyes to find Nell pulling Euru away from me.
>“Mmm?!”
>…Again. Nell’s face, smaller than mine, tilted upwards, and her lips met mine. Just like in the morning, a kiss with Nell followed immediately after a kiss with Euru.
>Her tongue slipped into my mouth. Just like with Euru, the intensity of the kiss made my head spin.
>This wasn’t right…
>“Do you understand now?”
>“Haa… what are you talking about?”
>“You said you didn’t understand why we were doing this. Do you understand now?”
>“That’s…”
>Sayo hesitated.
>‘She still doesn’t get it after all this?’
>“You still don’t understand, Sayo? Honestly…”
>“I’m sorry…”
>Euru, who had been standing a little apart, strode towards Sayo.
>“I thought our actions spoke for themselves, but since you don’t seem to get it, I’ll just come out and say it.”
>Nell stood beside Euru.
>“I love you.”
>“I love you.”
>“What…?”
>What had they just said? Love? Ah, they must mean… as friends.
HOLY FUCK THIS MC