lead diameter(s) mechanism composition variations production date origin	0.5 mm twist advance all metal unknown (1970s or 80s) Japan		I love the typography on the imprint of this pencil, but it is very small and does not show well in the scan, so here is a facsimile.
see also	Tombow (unknown model) thin lead drafting leadholder

This is a unique pencil. It has a micro-thin lead but uses a twist advance mechanism which is rather unusual in itself, but the really unique thing about it is the handle. I use the term handle rather than barrel because the overall anatomy of this pencil resembles a ruling pen. The handle is very thin and insubstantial. All the action is at the “nib” end.

This pencil shares a strange nose-heavy form with one from another Japanese maker, Tombow.