It's /ninja ni naru nui no maki/ - often people use the -nui in place of the classical negative ending -nu; but as this is naru, it's not working as a negative. There really wasn't anywhere else that I could slot nui in there, without just adding -nui at the end.
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But to go as far as using as a smokescreen to escape...She's really going whole hog here...Smoke's finally clearing...Shiranui Ninja Arts
Limitless Transformation TechniqueHere and now, the Tome of Shiranui Ninja Arts unfurls!The Scroll of becoming a Nuinja / FINDon't leave the thing that seems the most important to consult about for last!