Two excerpts from Nishikawa Joken 西川如見's Chōninbukuro 町人袋 ("Bag [of knowledge] for chōnin"):

Some say that the aversion to using the first, fifth, or ninth month for anything is hard to understand. Even accomplished scholars, when asked, say that they not know the origin of this custom. However, in Buddhist texts the first, fifth, and ninth months are known as something like "months of restraint and simplicity" [斎素月], and in these three months it is forbidden to put criminals to death or kill animals. The details can be found in the encyclopedias [事類全書]. In any case, this is a custom from foreign lands, and though in Japan these three months are particularly avoided, wicked deeds are wicked in any month — while good deeds must surely be even better during such periods. What reason is there for aversion?

As far as I was able to determine, identifying these three months as particularly hazardous for evildoers is a Chinese thing specifically rather than a Buddhist thing generally.

More:

Some say that even among the foolish doings of the children of this age, there are many which were passed down from days of yore for a reason. Here in this Latter Age [of the Law, 末代] some of these original meanings have been lost. In spring, many of the children of chōnin fly kites. The same is true in foreign lands. Even these kites have a purpose: because children are always full of yang energy/heat [陽熱], in the warmth of early spring their ki increases to excess; making kites and flying them overhead causes the children to look up open-mouthed, allowing their internal heat to escape upwards and preventing illness [...]

The more you know!

The modern Japanese word for "scarecrow" is kakashi. I had never thought much about what the etymology was until I found it in the Vocabularia in a slightly different form:

Cagaxi. Eſpantalho das ſementeiras per a eſpãtar os porcos do mato, ou veados.
Kagashi. Scarecrow of the sowing [?] to scare boars, or deer.

So the second /k/ was originally voiced. The current consensus (e.g. Maeda 300-301, Sugimoto 185) seems to be that the word shares a root with modern kagu "smell" and literally means something like "causer of the act of smelling", and that the original kagashi was not a human figure but a hunk of burnt game or clump of scorched hair tied to a stake, which quite understandably kept the animals away.

The usual way of spelling kakashi is 案山子, which is obviously not etymologically related to the word itself. Instead, 案山子 is a Chinese word, apparently imported in the Zen literature. It seems that 案山 referred to a relatively flat and accessible part of a mountain, where one might have a field for growing things, and 子 was added with its common meaning of "-thing", "-guy", etc.

Everyone seems to quote the same passage from the Transmission of the Lamp 景德傳燈錄 in support of this:

僧曰。不会。師曰。面前案山子也不会。

I'm a little leery of translating this without context, but it looks like it says:

The monk said, "I don't understand." The master said, "The scarecrow out front [or: in front of you?] doesn't understand either."

Works cited

• Maeda Tomiyoshi 前田富棋, ed.Nihongogen daijiten. Tokyo: Shōgakukan, 2005.
• Sugimoto, Tsutomu 杉本つとむ. Gogenkai. Tokyo: Tōkyō Shoseki, 2005.
• Vocabulario da Lingoa de Iapam. Nagasaki, 1603. Tokyo: Benseisha 勉誠社, 1978.

Here's something interesting in the Vocabularia da lingoa de Iapam:

Ienxǔ. Os da ſeita dos Ienxùs.

Zenshū. Those of the sect of the Jenxùs.

The initial <I> is "consonante", equivalent is the sound that in Hepburn romanization is written <j> in contemporary Japanese. I mentioned last time that the stage of the language described by this dictionary palatalized the /se/ mora, so you get shamishen instead of shamisen. The same went for the voiced version of that mora, giving jen instead of zen.

But the most interesting thing is that they define Zenshū 禅宗 "Zen sect" not by describing it but by referring to a loanword they already had: Jenxù, plural Jenxùs — and that loanword itself was probably from Zenshū!

Somewhat similarly, the dictionary uses the word fotoque (hotoke 仏, "buddha") in many definitions, such as nenbut (nenbutsu 念仏), defined as "Chamar, ou inuocar o Fotoque" ("call or invoke the Buddha"). But it does not have a definition for fotoque itself. I guess these were the sort of words that you were supposed to know by the time you arrived at your posting.