
In japan. If student graduate. 2nd button uniform of male students usually given to the person they love. 2nd button could be considered as confession. Because 2nd button is closest to heart. This custom of 2nd button in Japan is influenced by a novel and became habit of graduation day when people confess

i dont understand YA! WTF U DONT CARE! TWO RIVER FLOW IN ONE SEA ARE FOCKING SICK! it's like "OI BRO U DONE ME, NOW IT'S MY TURN" in relationships between FEMALE AND MALE woman can FCK man too LITERALLY by DILDO the problem that IF THAT MAN IS A CHip WHORE and will let it DO to him! AND if both like to be DOME they are BOTH WHORES! NO SECOND NO TOPS it's just the way u FEEL toward this relationship! IF U LIKE PERSON U WILL LET HIM DO WITH U ANYTHING IN DA BED! ヽ(`Д´)ノ

I'm Japanese and I went to junior high and high school in Japan. I think giving the second button doesn't necessarily mean a confession in the boy's part.
I think boys try to leave the second button for a special someone, or for girls they prefer most, but giving a second button is more like a keepsake and memorial to give to a girl to comfort her, since the boy's graduating and their ways are going to part. I think that's why the girl in the story was angry. She thought he should have at least given her mercy, and handed her the button to console her.
And the custom is to rip off the button in front of the girl so you can't really fool her about the number of button. Back in junior high, popular boys who were graduating had none of his button left, because girls were all over him and they were asking for what was left of his buttons.

Really? So the girls in japan actually flocking around popular guy? Like manga? Or just in graduation day? I mean, I can't imagine people gather around popular guy or girl because they idolize them. But friends flocking around is normal I mean not in idolize them. But thank you for your explanation :D

Here's something I found in another manga.
http://www.mangago.zone/read-manga/hidoku_shinaide/tr/v01/c016/pg-34/
See, Maya lost all his buttons on his graduation day.
It's just a tradition in Japan. And we also take pictures too.
What's the big deal with the hole, "2nd button" thing? Sorry but I just don't get it.