Straight to new girl with some drunken shenanigans, huh? Not even gonna bother confirming, or debunking what the readers are speculating this whole time immediately after teasing the readers about fMC not wanting to keep things secret from the MC? Really, author? Really doubling down on this "You (the readers) will never reach the truth." shtick? Schrödinger's Reader for this mangaka then.
We already know that the MC's childhood memory isn't exactly reliable initially, and is just starting to remember things as the story goes. There's a chance that college girl here is actually one of the girls in the picture from chapter 1, but had a huge change (or two) since. But hey, that's just a theory...
