Public Bath Manners (大浴場・温泉マナー - Sento / Onsen)
The strict cultural etiquette for utilizing hot springs (onsen) and public baths (sento). Always wash your body completely BEFORE entering the water, and never dip your towel in the tub.
Japanese communal baths are built to share pure, sacred therapeutic waters for mental relaxation, not for soaping and scrubbing. Thus, preserving water hygiene is paramount.
Undress completely (no swimsuits). Sit on a stool at the washing station to scrub before bathing. Keep your small modesty towel on your head or beside the tub.
What is the most crucial and strict Japanese rule that you must perform BEFORE entering the public bath tub/hot spring?