In a japanese style hotel, do i have to upgrade at 2am if i bring someone back to my room?

Question:

Long story short, I have tons of friends in Tokyo. They all don't live in Metro Tokyo. If I get a hotel room and end up meeting up with them, do i have to switch to a bigger room just to let them sleep in my room for the night? What if there are 2 of them? Could i face major fines just for being a good friend? Or would it be more like a slap on the wrist, like accidently sitting in the expensive seats on the shinkansen? I don't want to upset anyone but i also don't want to strand someone for meeting up with me too late.

Answer:

They will not allow you to accommodate more people than the number designated for the room. So you need to upgrade the room as you say.

If they found it, you have to pay fee for those people.