Where does “ashiyu” come from?

ashiyu (English) comes from Japanese 足湯, from Japanese 湯, from Old Japanese ゆ, from Proto-Japonic *yu — hot water.

ashiyu (English): A shallow communal pool in Japan, usually with seats around it, filled with warm water in which people can soak their feet and lower legs; a type of footbath

Definitions

A shallow communal pool in Japan, usually with seats around it, filled with warm water in which people can soak their feet and lower legs; a type of footbath

Ancestry of “ashiyu”, step by step

Step	Language	Word	Meaning
1	Japanese	足湯	a heated footbath, either as an appliance for one person, or as a communal amenity
2	Japanese	湯	warm or hot water; bathwater; a hot spring
3	Old Japanese	ゆ	attaches to the
4	Proto-Japonic	*yu	hot water

Every word from Proto-Japonic *yu →Every word from Old Japanese ゆ →Every word from Japanese 湯 →