back-to-back; facing opposite directions
Describes a physical arrangement where two people or things are positioned with their backs touching or facing away from each other.
The two sat back-to-back reading books.
This room is back-to-back with the next room.
two sides of the same coin; inextricably linked
Metaphorical use, often implying that two things are inseparable, especially when one is dangerous or undesirable. Commonly used in phrases like 背中合わせの関係.
Freedom and responsibility are two sides of the same coin.
Success and failure are inextricably linked.
on bad terms; at odds
Describes a strained relationship where two people are not getting along, often with a sense of mutual avoidance or tension. Frequently used with なる or だ.
Those two have recently fallen out with each other.
I'm on bad terms with him and can't talk properly.