Wikipedia
Nakazonae
are decorative intercolumnar struts installed in the intervals between bracket complexes ( tokyō) at Buddhist temples and Shinto shrines in Japan.
In origin they were necessary to help support the roof; however, at the end of the 10th century the invention of the hidden roof made them superfluous. They remained in use, albeit in a purely decorative role, and are typical of the Wayō style. The Zenshūyō style used by Zen temples has instead bracket complexes even between posts.