Sorry meant to upvote, btw I thought this too(I thought I was the only one who noticed about the theory of Jun being the son of Rio's sister
Hey! I’m the one who wrote the comment, and rereading everything, it is ambiguous who the mom is. I just assumed due to context clues, but it’s not super clear! Here’s some more ambiguous evidence tho to support why I was thinking this!
like how in Chap 1, the couple is talking about how the sister doesn’t want a family or home, which I took to mean that she doesn’t want to come home to the family she made.
In the chapter where they go to the beach and the kid mistakenly calls the dad ‘daddy’, the couple are talking about the how awkward the dad was and how the dad was a player and could’ve had a kid he didn’t know about, but then the chicken guy says because of that, they were able to have Jun. I took to mean that Jun was a the son of a past lover, and that because of his relationship they were able to have a kid.
But definitely the strongest evidence is the one you mentioned, where in Chap 1 Pg18, the dad refers to the guy’s sister as senpai, so that means he’s talking about how Jun is similar to the sister! And he’s talking about it as how parents pass their personality to their kids genetically, so that is definitely alluding the Jun’s parentage with the sister and the dad!
Then again, that’s just my theory!
I wrote a longer comment right below this one that hopefully explains everything better! Okay, I know I’m going overboard but I have F E E L I N G S about this manga!
Yeah it was your theory that I saw. While writing the comment I was actually so heartbroken, I looked at the bahasa Indonesia one cuz it's been completed but I cant read Indonesian lol.
Dang, I was sooo curious about the chicken suit so I read through the comments, then one of the comments had a theory that he was doing this so Jun can have the notion that under the suit was his mom, the sister of the the guy wearing the suit. And I was like, was it ever mentioned that the real mom was his sister? And then, I got, but that can't be, Im sure that the real dad is the guy with glasses (since the babysitter /best friend mentioned before that he hated that Jun resembled the glasses dad so much) and the Glasses guy and the chicken suit are so lovey dovey that I opted for the second theory that he does not want Jun to know that his mother is a guy and just thought there's a magical reason that he gave birth despite being a man (cuz that's what we want to believe). So I reread chapter one and I saw this
http://www.mangago.zone/read-manga/gin_no_kutsu/nbt/97deb765f3fa5a29/Vol1_Ch1/21/
Saying that he resembles him and 'senpai' referring to the Chicken Guy's sister. So in conclusion, Jun is the son of The glasses guy and his sister? And he's been taking care of the son of his lover and irresponsible sister, pretending to be his mom all the while hiding his face so Jun could still claim his sister as his mother and take all the love he nurtured.
How I want to be wrong T^T cuz if it's true I would be so sad.