Oh man, it was Rin. But I didn't care at the time. ouo;;
I do believe I was in elementary school when it happened... (Hey, yet again, I was using the come since I learned how to walk). I was looking for videos of pikachu when I came across a MMD PV for Kokoro. I watched it for a few minutes and decided I was on the weird side of Youtube. Now, so and so years later, I finally watch Kokoro again, hear "a robot built by a lonely scientist," and have several moments of "OOOOOOH."
So yes. But before I found Rin again, I was spamming my ears with Miku.