What Do You Call...? - The Box Knot

Whether in anime, movies or real life, you've probably seen kimono-wearing women who have their obi tied in what looks like a squarish box in the back. This is the most popular style of knot overall, used with Nagoya or fukuro obi for (outside of yukata) both casual and dressy kimono, and is called the "otaiko musubi"お太鼓結び, or "drum knot".

Women in komon kimono with otaiko knots.

Photo courtesy Wikimedia.

In an interesting bit of history, the drum knot gets its name not from its shape but the fact long ago a group of geisha invented the knot to wear to the opening of a bridge named Taiko (Taikobashi). Townswomen began copying them and the otaiko spread from there into standard kimono fashion.