So the author spoofed the name?
The app is not as well known in the west, so it doesn't work that well.
Maybe clarify that it's his contact info somehow? Maybe a small tl note? "Line is a messaging app"
I kid you not, right before I read that page I thought to myself "Man that photo looks nice, if I were in his shoes I'd to share that photo "
That was hella weird reading the 8th page after that, real weird, as if the onee-san is ubiquitous