Breakdown of senmenjo no kagami no mae de kami o naoshite iru to, imouto ga 「hayaku shite」 to itta.
Questions & Answers about senmenjo no kagami no mae de kami o naoshite iru to, imouto ga 「hayaku shite」 to itta.
Because で marks the place where an action happens.
In this sentence, the action is 髪を直している “fixing one’s hair,” and that action takes place in front of the mirror, so で is natural:
- 鏡の前で髪を直す = fix one’s hair in front of the mirror
By contrast, に is more often used for:
- destination: 学校に行く
- existence: 机の上に本がある
- specific point in time (in some cases)
So here, で is the location of the activity.
