This work is a window design for a fashion shop collaborated with a design company, TYMOTE. We were asked by the shop to design a window on the theme of “Letter”. This design composed by 1500 pieces of envelope and 200 pieces of postcard. By using the transmissive quality of envelope, we created soft curtain it’s like “Shoji”, Japanese paper screen in the shop. From outside of view, huge envelopes look like flying in the window. From inside of view, huge envelopes create patters of light and shadow. This is an enjoyable window design from outside and inside.