Apparently, since the flehmen response is only exhibited when animals smell things, usually pheromones used to mark territories and curl up their nose area and hold for several seconds to "investigate" the scent
Sorry to break it t you, but the original is in English, the author just wanted to do like 3-5 ch. for fun & said it would fry his brain trying to make a series.
Source: https://x.com/senukin69/status/1797345134952243565
That happened at least 7 years ago tho, so unless the dad assaulted a 5-y-o, I'm pretty sure its not her, she could be related to one of the SA victims tho, just like our MC