Hi there, my basis for calling this a shared path with bicycle-pedestrian segregation is based on the "Dedicated cycleway and footway" as shown in one of the examples on https://wiki.openstreetmap.org/wiki/Tag:highway=cycleway. Any other areas where I have added shared paths or dedicated cycle paths has been where they are similarly labelled to have some degree of separation between bicycles and pedestrians. 

As far as I can understand under Japanese cycling rules, you are correct in that cyclists can only use footpaths when the road is unsafe, but cyclists should use dedicated cycle paths instead of the road when they are available (as shown by https://japan.stripes.com/travel/know-rules-for-riding-bicycle-in-japan.html#:~:text=In%20principle%2C%20cyclists%20should%20ride,paths%20when%20they%20are%20available. ("Cyclists should use designated bicycle paths when they are available", & "Cyclists should use the lanes marked for bicycles on sidewalks or roads when they are available")). Because of this, where I have changed footpaths to shared paths, I have only done so where there is clear indication of a cycle path such as in the case you have highlighted, or the road is clearly so unsafe (multi-lane with high speed limits) that cyclists will always use the shared path. 

If I have missed something in my reasoning, please let me know as I do want to be accurate, but to me it seems that this is significantly different from a regular sidewalk, and the street appears to be designed for cyclists to use the designated cycle facilities as they have separation from pedestrians (although it is paint only).