expression, noun
A formal or literary euphemism for someone who has passed away, literally 'a person who does not return'. Often used in obituaries, elegies, or solemn contexts.
彼はもう帰らぬ人となった。
He has become a person who will never return (i.e., he has passed away).
戦争で多くの若者が帰らぬ人となった。
Many young people became the deceased in the war.