"Everybirdie" is just flavor; "everybody" when referring to birds. I just wanted to lay everything out. But all right.

Some people can interact with ghosts, and it's not too uncommon. No one really knows how, but personality seems to be involved - the characters who are closed off and prejudiced or consumed with hatred can't, the characters who are more accepting of strange things and people can. Yuuya's more on the open side.

Yuuya acts like he was already familiar with a ghost character, at least in passing, when he sees him. A few minutes later he sees a second ghost who he definitely never met and states that he's never seen him.