The yakko in hiyayakko
A friend demanded that I explain asked me about the word hiyayakko. Specifically, the hiya part is obviously related to words like hieru (become cold) and hiyasu (make cold), but what about the yakko?
I told him it was basically the same as yatsu, meaning "guy" or "thing" (as the kanji suggests). But he pressed on: why would such a general word be applied only to tofu?
I figured it was either that hiyayakko used to be used more generally, to mean "cold dish", and narrowed in meaning later; or that yakko meant "tofu" because tofu was so important to everyone's diet back then. But a few mimute's googling revealed that I had been completely mistaken.
Explaining this picture properly would take a whole other blog post, but I hope the crest on the sleeve is visible enough.
Turns out that yakko is an Edo-period expression meaning "in square blocks". This comes from the then-current usage of yakko (< 家つ子, "house boy"?): a brutally non-euphemistic word for a retainer, squire, or literal spear-carrier, serving but generally not of the warrior class.*
Anyway, the crests these yakko wore on their clothing, called kuginuki-mon (釘抜紋, "nail-puller [washer] crest"), had distinctive square patterns like the washers used in Edo nail pullers. From this tenuous link the association with squares was born.
Hence, yakko-dōfu is a square block of tofu, and the final transition to hiyayakko is clear.
Yakko live on today in kite form. Some say that these yakko-dako were intended as a sly dig at the upper class and/or their lackeys; all I can say is that something is up with all the goofy pictures of real, live yakko-dako that the Edoites left behind.
Charles:
I presume your reference to the yakkodako is the top kite on this page:
http://park3.wakwak.com/~eohashi/kanto011.jpg
About 10 years ago, I visited a kite maker and he seemed especially proud of a similar kite. He explained the symbology, I couldn't understand his obscure terminology, but I remember he thought they were hilarious. Here's a pic of him holding up that kite:
http://member.newsguy.com/~sakusha/kites/kites.html