元の木阿弥
(Moto no mokuami; “The former Mokuami”)

Definition:

Back to square one; ending up where you started. For something, or a situation, to revert to a previous (worse) state after temporarily improving. The ur-example is of a poor person who gets to live a relatively lavish lifestyle for a while before being returned to a hardscrabble life, but this idiom can apply to anything that gets worse again after getting better for a while, especially if the getting-better part required significant effort that in retrospect feels wasted.

Breakdown:

This simple idiom comprises two nouns, joined by the associative particle の (no). The primary noun is proper noun 木阿弥 (Mokuami), which turns out to be a guy’s name. The associated noun is 元 (moto), “origin.”

Notes:

Especially in an age of computerized auto-kanji it might be easy to forget that 木 can be pronounced moku and replace it with 黙 (also moku), “silent,” but this is an error. On the other hand, some variants may replace 元 with 旧 (“old,” “former”) without any change in pronunciation or meaning, or replace 阿弥 with 庵 (an), “hermitage,” or 椀 (wan), “bowl,” without any change in meaning.

This phrase supposedly comes to us from the Warring States period, when a feudal lord named 筒井順昭 (Junshou Tsutsui) passed away from sickness while his son was still a minor. To keep up appearances until his son reached the age of majority, the family looked for a body double and found a commoner named Mokuami. The latter was allowed to eat good food, dress in fine clothing, and generally live the life of the lord of a castle… until the son reached adulthood. At this point he was returned to his previous life as “the former Mokuami.”

Example sentence:

「パーティーの前に、せっかく全力を尽くして大掃除したのに、今この部屋を見たら、元の木阿弥になっててドッと疲れた」

(“Paatii no mae ni, sekkaku zenryoku wo tsukushite oosouji shita no ni, ima kono heya wo mitara, moto no Mokuami ni nattete dotto tsukareta.”)

[“I went and worked as hard as I could to clean everything before the party. But looking at the room now, it’s right back where it started, and all of a sudden I’m tired.”]