I was just wondering if there was any significance to the cross (like someone has put an 'x' across the picture) on certain manga covers. I noticed it recently with the titles Vampire-chan x Junior-chan, Koi desu ga Koi Janai, and Domestic Girlfriend. I haven't read any of these titles, so I don't know if their stories are similar or something that would give me an idea about why the X is there.
Just a little curious when I saw them in the updated section.
The uses of crosses is purely stylistic for different reasons, except for the right most one. There's no reason to imply that they (the first two at least) have any set or additional meaning beyond artistic flair.
The first one from the left mostly likely pairs symbolism of crosses and vampires. The second one from the left is there to imply a negative.
The title more or less translates to "it's not love, but it's intentional." The cross there likely represents an "X" implying that it's not something but intentionally there.
The third one on the right has a purpose, it's intended to associate to things together like Beauty x Beast. For a more detailed explanation consult this answer.
