I know this is, like, old now, but you know people keep coming back to read this, right? It's like one of THE pinfics. Anyway, regardless, I suspect you've already heard about pin singing a duet together (http://community.livejournal.com/___pin___/50102.html). There are (somewhat shakily-translated) lyrics here (http://maishampoo.livejournal.com/34725.html) and, omg, the part... well, you'll probably know the part I mean as soon as you read it XD;

...made me think of this fic SO MUCH and I may or may not have teared up >_>;

TT___TT I love this fic so much T^T