移流 is the most scientifically literal word in Mist Breathing's entire name-set, and that's worth pausing on. Every other form in this style reaches for classical-poetry vocabulary (八重, 遠霞, 朧) or invented-but-plausible compounds (霞散, 霞消) — words that sound like something out of a Heian anthology. Iryū breaks that pattern completely: it's a real, specific, modern meteorological term, the same one used in weather reports and textbooks to describe advection fog (移流霧), the kind that forms when warm air drifts across cold water. Naming a sword strike after a technical atmospheric process rather than a poetic mood is a small tell that Mist Breathing's imagery runs deeper than "mist is pretty" — it's actually tracking real behaviors of mist and haze, form by form, and Form Four is the one that borrows its vocabulary from a weather-science textbook instead of a poem.
VIZ's choice not to translate this literally is the more interesting editorial decision here. "Advection Slash" would have been a defensible, even more precise rendering — but it's also a word most English readers have never encountered outside a meteorology class, and a shouted attack name has to land in half a second of reading time. "Shifting Flow Slash" trades precision for immediate legibility: it keeps the sense of directional change without asking the reader to know what advection means. That's a different trade-off than Form One's translators made (they kept 垂天's classical density folded into a plain, readable image rather than explaining it) — but the same underlying instinct: technical or literary weight in the Japanese gets smoothed into something an English reader can shout along with.
The corpus's own English-alignment data for this occurrence is unreliable and worth flagging explicitly: the automated pipeline attaches the string "FOURTH FORM: ADVECTION SLASH!" to this page, but that text does not appear anywhere in the real VIZ volume — it's a fabricated composite produced by a page-alignment error (a known issue in stretches of Vol. 19). The actual printed VIZ line, confirmed by direct visual check one page later in the tankōbon, is "MIST BREATHING" / "SHIFTING FLOW SLASH!" with no explicit form-number caption on that panel at all. This entry uses the visually verified real rendering; the mismatched automated guess has been excluded from the citation record rather than repeated as fact.