Unable to answer "What’s the surface here?" – Foot Path – osm.org/way/771499609 via StreetComplete 60.1:

This way seems to have ceased to exist.

Attached photo(s):
https://streetcomplete.app/p/258834.jpg

This part is inaccessible to people in a wheelchair.
Also there is some information plate in Japanese and English about the history of this place.

via StreetComplete 58.0

Attached photo(s):
https://westnordost.de/p/221064.jpg