A home with lots of natural light is wonderful, but if you find yourself overheating in a midday sunbeam or making extended eye contact with your next-door neighbor, it might be time to buy curtains.

Designers Eiri Ota and Irene Gardpoit Chan of UUfie have completed the renovation of an apartment in Kanagawa, Japan, where the space is divided by two velvet curtains. Called Nagi, the 1970's ...