If you’re referring to the gray thing in the first couple of fish photos, they are also hook keepers . They are DRAGONtail Ultimate Tenkara Line Keepers . Sold by Dragontail Tenkara and also available on Amazon.
I use this particular line keeper when fishing the drop shot . I hook my streamer jig on my first rod guide and wrap my line under the line keeper to keep my lead in place .
Keeps my line and weight neatly on the rod when not being used.