Why are they doing that next to Belle's bedroom though?
Wise's room is next to Belle's room. Where else to do it? Wouldn't want to do it on the 1st floor store front, could muck up the video tapes. And doing it in the HDD room would probably be a bad idea as well with sensitive components. So Wise's room is the last place they have since from what we can explore, the twins don't have a kitchen.
Belle complains a lot that Wise always picks Ramen for them to eat at, so it seems they always eat out or do take out for dinner. The Twins don't cook at all then.
