RPGs’ obsession with having an “everyman” protagonist can do weird things to the story sometimes. Tsubasa is the character with a plot hook (the entire cast and audience at an opera performance vanished, including her sister, and she was the only survivor.) She has clear goals and a drive to achieve them. Itsuki is aimless and has no direct investment in the plot, but he cares deeply about Tsubasa, so he tries to keep her safe. Yet Itsuki is the protagonist and Tsubasa is the comic relief.