We did n't know that , so when we finally got back after having spent a while in out room changing for the ball , we thought we were over an hour late . Turned out the Cosplay Ball had started just a short time before . Lucky !

Question: Why were they changing ?
Answer: Because the ball just started a short time before .Because they thought they were over an hour late .Because they wanted to wear costumes for the cosplay ball .Because they spent a while in their room .