I am sorry I keep posting on my trip to Japan.
I visited a Japanese school while I was there in Ajigasawa, Aomori.
Visitors were required to remove there shoes and put on slippers.
The pupils were not allowed to wear outdoor shoes; they wore sneakers that were worn indoors only. But they had to remove these in the computer room (often in Japan, you are supposed to remove even slippers before stepping on carpet).
The teachers wore a mixture of indoor-only shoes. Some wore smart dress shoes; others wore sneakers or birkenstock sandals.