VIZ never romanizes this one — doing so would just be printing "Oiroke no Jutsu" as an untranslated pun, losing the joke entirely for an English reader who doesn't already know 色気 means "sex appeal." Instead the earliest corpus hits (Vol. 1 pp.14, 24, 67, 76, 80) settle on "NINJA CENTERFOLD" — a translation that swaps the vulgar-but-mild Japanese pun for an equally cheeky English one, evoking pin-up magazines rather than literally saying "sexy." That choice holds for over a decade of serialization: Vol. 49 p.49, deep into Part II, still renders a fresh cast of the same jutsu as "NINJA CENTERFOLD!!"
The technique's combined form with Shadow Clone — cast together on the same page in Chapter 1 to beat Mizuki ("ハーレムの術！！！" / "THE NINJA HAREM!!!!!", Vol. 1 p.80) — gets its own consistent, separate translation rather than being folded into "Centerfold." The corpus's later hit for the same combo (Vol. 71 p.48) shows the terminology shifting again, this time to "REVERSE HAREM JUTSU!!", with the surrounding Japanese-to-English narration in that same chapter abandoning euphemism altogether and just writing "The Sexy Jutsu is said to be more effective on stronger opponents!" in plain prose — the corpus's only instance of VIZ using the literal fan-term "Sexy Jutsu" instead of a localized alternative, a full seventy volumes after Chapter 1 first reached for "Centerfold" to soften the same joke.
There's also a one-off gag variant worth flagging: Vol. 38 p.146 introduces "おいろけ・男の子どうしの術" (literally "Sexy Jutsu: Boys-Together Version"), which VIZ leaves partly in katakana-derived romanization as "ART OF OTOKONOKO-TACHI" rather than translating outright — the only occurrence in this dictionary where a variant name gets punted to romaji specifically because there wasn't a clean English equivalent for the joke it's making.