Check the room, depending on person who is in there, Il say:
- "Sorry, wrong classroom." And go away..
- "Hmm...? I though there was suppose to be no-one in the art-room at this time of the day. So, if I may ask... What are you doing, looks interesting...?" And try to star conversation.
And if it happens to be a Fuuko, and if she says "Dozo!" Il just go straight ahead and hit her... And then Il leave the room.