The Ougi Clan uses an open fan as their clan symbol. The fans can be seen in various places: on walls within homes, on flags on property, and also on the back of clothing.
Curiously, different clan members do not seem to use the same fan. This may be a matter of personal preference, but it may also highlight a division between the main branch (Legitimate Successors) and lesser branches (non-Successors).
In the manga, the road outside Ichirou Ougi's home is lined with black flags bearing solid white fans.
Shichirou Ougi has two different upside-down fan designs for his clothing. One is a solid black fan, worn on a white jacket, and appears to be for casual dress at home. The other is white fan bearing a scythe-wielding Grim Reaper, worn on a black coat, which Shichirou has only worn during his work as an assassin.