When one of the four seats is empty, nobody sits in it. I thought it was a rule, but apparently it's just habit.

• Ayu (Ayupan)It is a rule. I made it.
  MomoYou didn't say anything about it yesterday though.
• MidoriIt's better to leave the seat empty. If there's someone who might come back.
  MomoMidori, sometimes you say scary things in the prettiest way.