Subaru Shidou is one of the few selected to be a hostage in Hogstein's theme park, he was in charge of security for the park on the opening day, before Hogstein hijacked it.
Shidou acts as the detective of the group, calm, collected, observant, but strict. He has a strong sense of justice and is always the first to volunteer if something seems too dangerous for civilians, additionally because he feels responsible for everyone being trapped in the park in the first place.
He constantly wears his sunglasses, even at night, due to his eyes being sensitive to light.
Shidou explains that he doesn't want to see anyone hurt because of his failures and goes on tell the protagonist that when he was a rookie cop, his partner was shot and killed during an altercation. He has felt responsible for his death ever since and doesn't want to be the responsible for someone else being hurt or killed again.