Ninjutsu is a Custom Skill used by Akatsuki Akashima. It allows him to use Sword Based Martial Arts Skills used by Samurai and Ninjas. Akatsuki like his other skills managed to import this one as well.
This Skill Allows the player to completely blend the Nihonto , Parry, and Martial Arts Skills to use Sword Based Martial Arts techniques akin to those used by samurai and ninja alike. It is similar to Battoujutsu and can rival the aforementioned unique skill. It is leveled up through proficiency in all three of it's parent skills.