I did receive yesterday a box of OWNER Micro X Eyeless hooks , this product is not new but there is only merchant who stocks this reference in the West.
The size of these hooks is 5.5 Gou (号) and they are the smallest eyeless hooks I have tried until now. I was told by my friend Bo Rovan that Gou is a Japanese measure unit for diameters. As it happens these hooks have a 0.37 millimeters diameter.
A few weeks ago a Japanese friend of mine taught me that these hooks were designed for Ayu fishing in which their particular shape was essential for a good hook setting.
These hooks are made of fine wire, supple yet strong steel; I did catch a lot of trouts with the bigger sizes last season and I never had a break neither a twist. This is Japanese steel!
My opinion is that one has to try these very light hooks not to fish on "exotic" dry fly patterns but to fish with light wet flies and thus understand the great advantages of Tenkara in the drift control issue.
Each box of these hooks contains 120 pieces and that's a good way to occupy the long winter evenings!