You can create ninjutsus in written form called Makimonos.
Prerequisite(s): Caster level 1st, Ninjutsu class feature.
BENEFIT
This feat counts as Scribe Scroll for prerequisites and functions like the feat, but only for Ninjutsu’s from the ninja spell list. Scrolls made this way are used in the same manner as regular scrolls. A Ninja can learn additional ninjutsu from these scrolls, and can use these scrolls without making a Use Magic Device Check nor does he need to decipher the scroll. This feat counts as Scribe Scroll for prerequisites. You can create an Makimono of any ninjutsu that you know. Scribing a makimono takes 2 hours if its base price is 250 gil or less, otherwise scribing a makimono takes 1 day for each 1,000 gil in its base price. To scribe a makimono, you must use up raw materials costing half of this base price. You cannot scribe multiple ninjutsu into a single makimono. Makimonos work just like Scrolls, but can only contain ninjutsu.