You could make a case for sound based genjutsu being above base sharingan and arguably ms because it can affect multiple people.
Anyway ill say this.
That technique is sharingan based. It requires the sharingan [
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Besides i am not sure why you are surprised. Its been above roughly 300 chapters ago that itachi told us that he doesn't need his sharingan to cast genjutsu.
Likewise its been roughly 5 years or more that the 3rd DB stats were published and in that itachi gained a 5 in this field.
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Little alarming that at this stage in the manga questions are being asked about this