The Kuru Toga ,Japan made unique mechanical pencil,has a core rotation mechanism that continually rotates the pencil lead as you write. The lead is twisted through a spring-loaded clutch, it works by twisting incrementally every time you lift the pencil up. This allows a uniform wearing of the pencil lead so that it always remains as a pointed tip.
Not only does it solve the problems such that the point is worn down and thus your line widths are not uniform as as you continue to write. but it also gives you an amazingly thin line. You are effectively using only 50% of the lead area that you were previously using with your old mechanical pencil.
Thus, a 0.3 mm Kuru Toga will write incredibly thin lines and have less breakage than a standard 0.3 mm mechanical pencil.