Ito-ya is a massive paper products store. I think Ginza has the main branch. There's also one in Shibuya.
They sell anything related to paper, such as : greeting cards, washi, note pads, diaries, stickers, paper dolls and wrapping supplies. They also had a selection of souvenirs, such as Japanese hand towels. They had walls and walls of washi paper, and it was really difficult to choose - I wanted them all! I went a little nuts in this shop. I bought a few Hina Matsuri cards as gifts. There's something so elegant about Japanese greeting cards.
I think I'll make some dolls from these papers. One could even just frame these papers as they are so beautiful. I definitely recommend this store. Credit cards are accepted and you can claim a sales tax refund if you are a tourist, so bring your passport along.