AirBnB in Tokyo allowed?

I'm planning to buy an apartment in shinjuku-ku. However, I will only live there about 4-5 months in a year since I spend most time abroad for business reasons. So I was wondering how I can reduce my costs, and airbnb or similar comes to my mind.

After some research, it seems I'm limited by renting it out max 180 days (nights) per year, which is not a problem at all. But two things I wonder: 1.) will I need the consent by the other apartment owners in the building? And 2.) are there any special rules in Tokyo or Shinjuku that might be a problem?

Lastly, I suppose it will not be a problem to have a home loan in that case, but does anyone know what the loan contracts usually say? Do they put restrictions on renting it out temporarily?

(I can easily prove via plane tickets that I'm out of the country during any rental, in case that's helpful/necessary)

Any resources would be appreciated!

by AmumboDumbo