捕らぬ狸の皮算用
(Toranu tanuki no kawa zan’you; “Calculating the pelt of an uncaught tanuki”)

Definition:

Making over-optimistic calculations. Building unreliable assumptions into your plans for the future. Making a budget that includes estimated profit from the sale of the fur of a tanuki you haven’t actually caught yet. Counting your chickens before they hatch.

Breakdown:

This is a noun phrase in which all the other parts modify the final noun, 算用 (san’you), “calculation.” This is modified by attaching the noun 皮 (kawa), “animal skin.” The origin of the skin is specified by using the associative particle の (no) to connect it to 狸 (tanuki), the Japanese “raccoon dog.” Finally, at the start, we have a verb that specifies the state of the tanuki whose pelt is being calculated: 捕る (toru), “capture,” in imperfective form with the negative suffix ず (zu) in prenominal form.

Notes:

The initial verb can also be written as 取らぬ, 獲らぬ, or phonetically as とらぬ, without any change in meaning or pronunciation. However, writing kawa as 革 – despite it being to a degree semantically and phonetically interchangeable with 皮 – is considered an error. The phrase may be invoked in abbreviated form as 皮算用.

Tanuki fur was apparently used in both winter clothing and writing-brushes, and a pelt could be sold for a high price. However, Japanese folklore ascribes to the species a variety of magical powers such as shapeshifting, so trying to catch one may be thought of as a somewhat daunting task.

One of my sources claims that this is the と entry of one of the iroha karuta sets. If so, though, it seems to be a nonstandard set.

Example sentence:

「ボーナスを手に入れる前に何を買いたいかなんて話は捕らぬ狸の皮算用に過ぎないと思うけど…」

(“Bonasu wo te ni ireru mae ni nani wo kaitai ka nante hanashi wa toranu tanuki no kawa-zan’you ni suginai to omou kedo….”)

[“I’d say that all that talk about what you’re going to buy, before the bonus money is actually in your hands, is nothing more than counting your chickens before they hatch.”]