probably rice starch glue.

@@thesage1096 Probably rice or fat/bone from animals. Easier to remove and re-apply as well.

There are wooden doors called amado that you can (should) put up/shut when there is a big rainstorm. and the roof overhangs enough to protect during light showers (if there is not too much wind). Also merely wet paper will dry. Replacing is for when it's damaged by dirt, tears, mold, etc. In modern houses, shoji are only inside the house, either as partitions or acting as interior windows behind which there is a standard, modern window, so no rain issue. Unruly children or pets are a bigger risk. I also have damage on the paper of one shoji due, I think, to the fact that the paper was replaced when the air was too humid, too soon after a small water damage elsewhere in the room; the paper teared along the border, and I think this due to normal shrinking when the air got dryer. Planning to replace it now, which is why I watched this video.