So I was just talking about the differences between how ninjas are portrayed in Japanese folklore versus how they’re portrayed in popular culture, and one of the topics that came up was so-called “ninja magic”.
Basically, while popular culture depicts ninjas performing supernatural feats of stealth and swordsmanship, the folkloric version is rather different. Ninjas in folklore are reputed to be able to evoke magical effects from specially prepared potions and powders through the use of complicated hand-signs and invocations. The effects of these formulas can range from controlling fire, to turning invisible, to paralysing enemies at a distance, and even stranger feats.
Then it hit me: ninjas go unarmoured, wield staves and daggers, and cast formulaic spells that must be prepared in advance and have verbal, somatic and material components. This leads to one of two possible conclusions: