Responses
I think it's different manga. I read the one about the youngest bro and it's not that he found out suddenly or something, he just knew it by feeling and decided to never confirm it for eldest bro's sake, so there's no way he would freak out. If anything, the one who freak out a little is youngest bro's boyfriend
On myanimelist it says this manga has 7 chapters but here are only 5... is it incomplete???