(Tori naki sato no koumori; “A bat in a village without birds”)
When there are no exceptional people present, ordinary schmucks will talk big and throw their weight around. My sources compare it to “In the land of the blind, the one-eyed man is king,” although the feeling is probably closer to “If everybody is blind, then some random blind guy will act like he can see.”
This week’s kotowaza is a noun phrase. For a change of pace (and because it’s often the logical way to approach Japanese-to-English translation), we’re going to read this one from right to left.
The noun 蝙蝠 (koumori) is bat(s), as in the animal. (Keep in mind that without additional information, almost any given noun in Japanese could be singular or plural.) Everything else in the whole saying works to modify this one noun. Working backwards, we find the associative particle の (no) connecting the bat(s) with the previous noun, 里 (sato), “village.” (The character can also refer to a unit of distance or a ten-to-fifty-home administrative division, depending on the time period, under the old ritsuryou system.) What kind of sato is it? – you ask, which is nice of you because I happen to have the answer. It is a sato where 鳥 (tori), “bird(s),” are 無い (nai) – a negating adjective, here in prenominal form.
And there you have it: “The bat(s) of a birds-are-not village.”
蝙蝠 is usually written in kana (こうもり) rather than kanji in everyday usage (not that most people use it very often), so don’t let the rare characters put you off. (Do use the kanji for writing this saying, though.) 無き can be written with or without the kanji without any particular change.
There are many versions of this saying. The closest simply changes 里 out for 島 (shima), “island.” Others use different animal pairs, talk about which small/prey animal is “king” when the larger or more predatory animal is absent, and so on.
(“Sannensei-tachi ga juken benkyou no tame ni renshuu ni konakunatta ya ina ya, tori naki sato no koumori no you ni ninensei ga ibarihajimeta.”)
[“Almost before the seniors had stopped coming to practice so they could study for their entrance exams, the juniors started getting pushy, like bats in a town without birds.”]