A Hanzo Shinobi investigates it

While enforcing public morals via ninja magic can usually work on someone via subconscious suggestion, it isn't all that effective on a shinobi. Nevertheless, Hanzo Academy raises only good shinobi. Since most good shinobi already uphold those kinds of values, the scroll's effects are still very hard to notice even to a trained ninja. If it were to be noticed, hypothetically, it would need to be a shinobi student with values that differ significantly from the Rules.

In terms of the current pool of shinobi students at Hanzo, only two candidates stand out as ones with moral compasses at all perpendicular to the one set out by the Rule Scroll:

1. Daidouji, boasting a delinquent's appearance and demeanor. While her immense physical strength is an obvious boon to the Academy, her values only include one thing which is power. Even without much intelligence to balance out her strengths, she probably would take notice if something was trying to make her think about something else. Additionally, she is the school's longest running student, never actually graduating, so she would have the most experience with the Rule Scroll's effects.
2. Katsuragi, who has a single-minded commitment to her own love of boobs and utopian vision of a world where her sexually harassing behavior flourishes unobstructed. When there's a will, there's a way, and by far the most powerful **** of will in the Senran franchise is Kat's desire to get her grope on.