Did I miss something, or did this just come out of nowhere?

MC just gave a flashback about a fox he saved and the reveal that ML is that fox. Did they mention that before? If not, that's a really weird thing to bring up. It's not a plot twist for us because it's written like it's information we're supposed to know, but I'm really confused.

And again: stop doing the "I knew you since you were a child and I was a grown adult" trope, please! And the MC hasn't aged AT ALL. I'm not mad at him, but dang.