Don't know how long this will be up, but I found this on ayu's official youtube channel:
http://youtu.be/nmL5shr_OdM
I romanized the lyrics as well (These should be pretty accurate).
ano natsu no omoide wa
ima mo mada azayaka na mama
itsu datte omoidasu nara
anata to futari ga ii
ano natsu no omoide wa
ima mo mada azayaka na mama
itsu datte omoidasu nara
anata to futari ga ii
on friday nite me to me ga atte
on saturday chikatsuita ne
on tuesday tashika ni natte
on friday nite megutta
ano natsu no omoide wa
ima mo mada azayaka na mama
itsu datte omoidasu nara
anata to futari ga ii
muchuu ni natte koi shite
sono uchi ni ai shite
sore ga unmei nan da tte shinjite itakatta
lalalalala......
ano natsu wa omoikiri
hiyake shita hada useawatte
sakendari naitari shite mo
sore demo tsutaetakatta