Haruka naru yama no yobigoe (1980)

Drama
-Year: 1980
-Year in film: ~1980 ?
-Country: Japan
-Who in bibs: boy ~8 ?
-Available on DVD: yes 
-I own: no
-Bib occurrence: low-
-Rating:  3/10
-Rating: ***
-Comment: One young boy in dark blue bibs, maybe raw denim, front and rear view. Although depicted on the cover I only found a very brief scene at 1h50. Farm setting and riding but I think not in bibs.

English title: A Distant Cry from Spring (aka Echo of the Far Mountain). Japanese title: 遙かなる山の呼び声.

There is also a 2018 remake with at least a lady in bibs or similar.  

Update: Searching with the Japanese title, I found 2 more scenes of the boy, riding in bibs and standing full view, distance. Obviously brief scenes as well.

The remake turned out to have a long apron and I haven't found any bibs scenes.