The Yamaguchi prefectural tourism site puts the season here at late October to mid-November. Chomon-kyo is the middle stretch of the Abu river, a gorge straddling the boundary between Yamaguchi city and Hagi, and a nationally designated place of scenic beauty.

A path of about 5.1 kilometres runs along the water, and walking it is the way the place is meant to be seen. The scenery changes as you go rather than arriving all at once: odd rock formations, fast water, then deep still pools. Roughly halfway there is a teahouse, Suzu-ga-chaya, set close enough to the river to hear it while you rest. The far end is Ryugu-buchi, and that stretch — roadside station to Ryugu-buchi — is the standard walk.

In some autumns a shuttle bus links the two ends of the path so that walkers do not have to double back. In other years it does not run at all. It is worth confirming before you plan a one-way walk, because the alternative is ten kilometres rather than five.

The gorge is rich in more than trees. Fish, birds and butterflies are all abundant, and the Abu is known for its ayu, eaten here in summer. Autumn is the other reason to come: the maples along the water turn hard enough that the surface takes the colour. The roadside station at the entrance sells Ato beef and makes a reasonable stop either side of the walk.