Four-Character Idiom · Reflection & Mortality · Kyojuro Rengoku
Meaning
A relationship or value-system so incompatible that the two parties cannot live under the same heaven — a classical Chinese articulation of irreconcilable opposition.
共に同じ天の下には生きられないほど、絶対に容認できない関係性や価値観の違い。
The Kyojuro Rengoku line
Verbatim from the source article
「君と俺とでは価値基準が違う」
"YOU AND I VALUE DIFFERENT THINGS."
Why it fits Kyojuro Rengoku
Rengoku's flat statement that he and Akaza operate by different value scales is a polite Japanese surface over the classical position of fugu-taiten. The two of them cannot share a sky; the fight that follows is the geometric consequence of the sentence.
Cultural note
Origin in classical / Buddhist / Confucian tradition
From the Book of Rites (礼記): a son cannot live under the same heaven as the killer of his father — an absolute moral incompatibility, not a personal grievance.
Sources
- デジタル大辞泉 — 不倶戴天 (dictionary)
- 精選版 日本国語大辞典 — 不倶戴天 (dictionary)