@Akemua Maybe I’m misunderstanding what you’re saying, but she didn’t post the pic publicly. She just sent it to him privately. And no she didn’t need to show the underboob, but did it to make him flustered. Honestly can’t tell if you’re being sarcastic or not, so I answered your question.
@Liquidsword - Well, I just thought of this as a chill kind of manga, so it just seemed weird to me she would start posting semi-nude pics just for him to get jealous. I totally forgot DM's exist because I don't use social media. Him saying she shouldn't show too much skin to people kinda reinforced that though ( at least that's what she thought he would say).
After reading it through again, it makes more sense she was just trying to mess with him. So my comment was me more or less misunderstanding of what was going on.
@Akemua Not necessarily jealous, but embarrassed. I mean, it is a chill manga, but she’s been trying to seduce him since the beginning. She’s always been pretty revealing to him, so the pic wasn’t really surprising or weird IMO.