Halloween.
It was a western holiday. Dae-hyun's memories of it mostly involved English teachers and English class, and he'd stopped going to hagwon the minute that debut started looking like more than just a pipe dream. He had never really thought about it much.
He hadn't expected to do anything. They hadn't debuted yet, just started training together, so it wasn't as if the company expected anything from them or that they could host their own event.
The whole thing was just Yo-han's idea.