Ichimon bashi is the bridge by which the Saigoku Kaido crosses over the Obata River on the border between Muko City and Nagaokakyo City. Obata River used to flood frequently. The floods used to destroy the bridges and it was necessary to collect a toll called 'Ichimon' from everyone passing over the bridge in order to build a replacement bridge. That is how the bridge acquired its modern name.