The ex-rail route also goes through pretty farmland and paddy country before depositing you in the middle of nowhere around the Yamakuni area, a few kilometers from Hita. From that point, it's back on the regular roads... but there's not likely to be much traffic anyway.
Probably the most spectacular sight on this route is this amazing arch bridge (one of several). You almost feel guilty cycling over this and knowing it's for bicycles only...