Today’s kotowaza, in English terms, is more of a set phrase than a “saying,” but it’s a kotowaza in Japanese none the less.

背水の陣
(Haisui no jin; “An army with its back to the water”)

Definition:

Having your back to the wall. Being backed into a corner. A tight spot without room to maneuver in. A situation where, if you mess up or fail, there are no second chances: you can’t regroup and try again.

Breakdown:

The nouns 背 (“back,” in the compound pronounced with the Chinese-based reading hai) and 水 (“water,” similarly pronounced sui) make what is effectively a compound noun. The associative particle の (no) connects it with the noun 陣 (jin), a military camp or formation. So 背水の陣 depicts an army drawn up for battle with its back to a river, lake, sea, or other body of water.

Notes:

Like so many others, this phrase comes from Chinese antiquity – specifically the Battle of Jingxing, in which the Han general Han Xin purposefully arrayed his forces with their backs to a river so that they would fight more fiercely.

Example sentence:

「今年合格しないと、貯金が底を突いてしまうんだ。今回の入学試験は背水の陣のつもりで頑張る！」

(“Kotoshi goukaku shinai to, chokin ga soko wo tsuite shimau nda. Konkai no nyuugaku shiken wa haisui no jin no tsumori de ganbaru!”)

[“If I don’t pass this year, my savings are going to run out. I’m going to work on the next entrance exam like it’s victory or death.”]