When I lived at home my mother was like that too.  
I used have to smuggle things that I baught into 
the house when she was out.  Sometimes things sat 
in my car for days because I couldn't bring them 
into the house.  My mother deemed anything that 
wasn't useful (books, clothes) or a "good" 
collectible (ie. crystal or china) to be nonsence, 
so I got a lecture each time I got caught with a 
new "toy" and I endured it demurly without saying a 
word.
Now I look back at what I went through and I am 
wondering why I never stood up for myself and told 
her that this is what I collect and that she should 
deal with it.  

I wish you luck with your trip to Japan.

Evil Jew