I’m always a little bit nervous when hitchhiking in a new country, especially where there’s a language barrier. But Japan is great to hitchhike! People know the concept (pronouncing it ‘hitch hike’, emphasising the space between the two syallables). We also saw some Japanese hitchhikers.
To hitchhike, you do the same as you would in western Europe, and stand with your thumb out. Sometimes we used a sign, sometimes we didn’t.
Waiting times were similar to in Europe, ranging from three minutes to three hours.

Hitchhiking at the exit of a rest area. We have a sign which may or may not say ‘west’!