inadvertently; without thinking; for no special reason
Colloquial adverb used when someone does something casually, unintentionally, or without a clear purpose. Often interchangeable with 何気なく, but 何気に is more informal.
unexpectedly; actually; truthfully
Used when something turns out to be surprisingly good, true, or contrary to expectations. Often carries a nuance of 'to be honest' or 'come to think of it'.
without realizing; before one knows it
Describes a change or state that occurs unconsciously or without the speaker's awareness. Similar to いつの間にか, but more colloquial.
A casual remark I made without thinking hurt him.
I turned on the TV for no special reason, and the news had just started.
Actually, this shop's ramen is surprisingly good, isn't it?
Truthfully, I hear he's quite wealthy.
Time passed without me realizing, and it's already evening.
Before I knew it, I had fallen for her.
Derived from the adverb 何気なく (なにげなく) by replacing the adverbial ending 〜く with 〜に, a pattern seen in other colloquial adverbs. The exact origin is uncertain, but it likely emerged in casual speech.