Hi, the footpritns you mapped here represent buildings. You correctly excluded what appear to be (white) tarps from some building footprints.

For my feedback I will focus on https://pewu.github.io/osm-history/#/way/1430792920 . 

You outlined both the roof and walls of this building resulting in it being oversized: 192 square meters compared to 150 the way I mapped it. Here the North and Eastern walls are visible and shadows are cast NW. Please read https://wiki.openstreetmap.org/wiki/Roof_modelling and watch https://youtu.be/JAPiGntG6fs

As I mentioned before in my comment on Changeset: 171090518 you should proceed with caution when using the Japan GSI seamless layer, because the angle it is captured at changes frequently, making it more difficult to know when you're looking at a building's walls. I recommend cross referencing other sources to aid your interpretation. Idealy one taken from a different angle and with shadows cast in a different direction.

I'm assuming we have permission to use Japan GSI standard Map when contributing to OSM. It looks really useful especially for toponomy, but please compare it with the imagery; to me the footprints do not always appear accurate. For example I see no evidence in imagery to map the footprint I've been discussing as anything other than a rectangle.

https://pewu.github.io/osm-history/#/way/1430792915 is positioned a few meters away from being in alignment with features in its vicinity. Try to improve it. If you choose to do so, then please send me a link to the changeset.

I hope this is helpful. Thank you for your contributions!