Damnit. I finally understand what's going on. Had to check the raws to find out that, technically, a page is missing.
It's just text, but from what I understand it's the first time the MC actually speaks (remember that the chapter titles are his thoughts, not him speaking to the FMC):
"Can a bully like you make me happy?"
To which the FMC replies with slapping herself and swearing on it. (Edit: after more discussion, I'm not as sure that it was really her slapping herself. Check out these comments:
1 and
2.)
Both groups have made a mess by assuming this line is a title, then separating the two drawn images into 15.1 and 15.2.
I only realised something was wrong because the release by spinning_donuts got a chapter title, but not this one.
@vipguy64, can you fix this? It's a shame that this mistake brought so much confusion.
I reckon it's because on Twitter the author just used text for the MC's dialogue:
But on his Fanbox there's a whole white page for it:
Just to reiterate, the use of 「」 indicates dialogue. And I think following the Fanbox format gives it better impact. These should never have been separated.