Before the war, Japan's fountain pens were commonly equipped with a grind made to emulate brush strokes with thin vertical lines, thick horizontal lines, and a sharp hairline at high angles. Revived by Nobuyoshi Nagahara and passed on to his son Yukio Nagahara, the Naginata Togi grind has found fame as a bespoke option from Sailor. Yukio Nagahara offers a similar grind that he has named the Kodachi. Yukio Nagahara has granted Matthew permission to offer the same grinds as he does.
Kodachi nib is designed to recreate brush strokes for Japanese and Chinese calligraphy when used a certain way. For western writing it will act like a very forgiving architect that has line variation depending on the writing angle.