I read a blog by a Japanese quilter named Ayumi. She used to live in the US and married an American, and about a year ago, they moved back to the Tokyo area. I have emailed her in the past and she responded promptly to my inquiry, so I would suggest you email her. You can contact her through her blog:http://ayumills.blogspot.com/
I am sure she can recommend where your son can get you some fabrics to bring home.