This is a similar case as the Yasukinu Jinja issue...

About 15 years ago I went to Akihabara for a computer purchase. Since I
wanted to compare the specs and prices in various shops, I made some notes.
A salesman come up to me and told me to stop writing.  I gave him a polite
but determined response to get lost. A minute later I was approached again
by the store's manager who told me the same and threatened to call the
police if I didn't comply...
Since I had already everything I needed,  I just left and bought the system
elsewhere.
Does anybody know the prevailing Japanese law about this one? I should have
the right to make notes in whatever form I want. I am no genius who
memorizes tons of data...
On the other hand, I had the same trouble twice in a department of a German
home center where I was even banned from revisiting by the chief of the
house for not complying. Since there were plenty of  other outlets I
couldn't care less.
I know that restaurants and other private enterprises can refuse customers
for various reasons.


Sigi