expression
no concern of mine; nothing to do with me
A set phrase expressing complete indifference or detachment, often used when someone refuses to get involved or feels unaffected by a situation. Literally 'I am not concerned'.
See also: 関する
彼はいつも我関せずという態度だ。
He always acts as if it's none of his business.
周りが騒いでも、彼女は我関せずと本を読んでいた。
Even when everyone around was making noise, she kept reading her book as if it had nothing to do with her.