Nightmare and Error

(Dream and Cross's Wedding (Nightmare was the most powerful Mafia Boss, and Error could do any job perfectly and was the best hitman, feared by all Mafia bosses. Error was invited to the wedding by Cross as a bridesmaid. Nightmare was invited by Dream because they were brothers. Error didn't know that Nightmare was Dream's brother, so when he asked Nightmare for time off from work, Error simply said that his friends had invited him to the wedding.) It was now evening. Error was trying to brighten the gloomy atmosphere in the hall, and when they started bringing out the cake and seating everyone, Error calmly sat down in his seat not far from Cross, but suddenly he noticed that Nightmare, who was sitting next to Dream, was sitting across from him at the table.)