Honyabakei is a small town south of Nakatsu in Oita Prefecture. in 2005 the town was merged with Nakatsu.
The draincover depicts Yabakei Gorge and Aonodomon.
The gorge was created by the Yamakuni River cutting through the biggest volcanic plateau in Japan.
The result is some spectacular rock formations and sheer cliffs that are particularly popular in the Fall season.
Aonodomon, which means "blue tunnel" is an almost 200 meter long tunnel carved into the base of the cliffs. According to legend it was carved by a single monk named Zenkai using a hammer and chisel and took him 30 years to complete.
Earlier in his life Zenkai had committed a murder and to atone for his sins her carved the tunnel to make the rout to a local shrine safer for pilgrims.