"
Eeteru masui no tsumetasa
Nemurenai gozen niji
Subete ga kyuusoku ni kawaru
What Rin is singing is after "City lights ornate" is: "Coldness of Eeteru anesthesia.
The sleepless morning rainbow.
All changes rapidly"
Which anesthesia means pain so Rin is probably feeling pain and it could be from a vocaloid, even her own twin brother Len.