Register at Foreign Bureau?

You can do the 144 hour transit (its not a visa but transit without a visa)without a hotel. You and your friend will need to appear in person at the local PSB to register within 24 hours of arrival.

PSB = Public Security Bureaus
usually its at a police station

ok, but is it ok to just do it once, or do I have to do it every day?

Just once is ok, but your friend must accompany you and you must have all the relevant documentation including lease, etc. To be honest, it’s much easier to book a cheap hotel for the first night and let them handle your police registration.

Ok, she is staying at a kind of hotel apartment. I guess they have a reception that can help me with that?

That depends on what the "hotel apartment" is. If you are talking about a standard condominium with concierges and securities then they can't register you because it's considered a private residence. There are also "self-service hotels" similar to little condos (with kitchens and everything) that are classified as hotels. The staff there will register you if they are licensed to accept foreigners and will send you away if they are not. Talk to your friend to see what kind of place she lives in.

Ok, thank you for the reply. I think it is classed as a hotel. Looking at their web-site, anyone can book a hotel room online so that feels like it is a hotel. I will ask my friend to check in the reception if its possible.