Here's a dubious but fun idea from Nihongo no rekishi 日本語の歴史 ("The History of Japanese", ed. Kamei Takashi 亀井孝, Ōtō Tokihiko 大藤時彦, Yamada Toshio 山田俊雄): yō (appearance, way, manner, thing, etc.) as a straight-up Japanese word, not a borrowing from Chinese.

In a section discussing the possibility of the earliest known stages of Japanese being several distinct dialects recombined shortly before people started writing things down, Kamei et al note that constructions like /omofaku/ 思はく and /ifaku/ 云はく, which are hard to translate but sort of mean "thinking" and "saying," are paralleled by constructions like /ifu yau/ 云ふやう with similar meanings. The argument is apparently that although this /yau/ (yō in Modern Japanese) is assigned the kanji 様, it may actually derive from an earlier form like /yaku/, which would in turn share a common ancestor with the /-aku/ of /ifaku/. Brothers separated at birth, growing up in different dialects, and brought together again at last after some kind of political unification.

The first and most obvious counter-argument to this hypothesis is that bare vowels like the /u/ in /yau/ are only supposed to appear word-initially in Old Japanese: /yau/ shouldn't even be possible as a native word. The second counter-argument is the deeply suspicious timing of /yau/'s appearance: it can't be found in the Manyōshū (while /ifaku/ and /omofaku/ are in there a handful of times each), and the 日本国語大辞典 ("Shogakukan Unabridged Dictionary of the Japanese Language") goes so far as to say that it doesn't appear at all in Old (上代) Japanese, and didn't reach its peak until Late Middle (中世) Japanese.

To get around these problems, we end up having to argue that /yau/ remained hidden from Old Japanese in a related dialect that did allow bare vowels in the middle of words, only to be suddenly re-incorporated into the mainstream of the language just in time to look exactly like a borrowed Chinese word at a time when a lot of borrowed Chinese words were floating about. This seems an awfully long bow to draw, and I remain unconvinced.