
It doesn't say clearly anywhere, that's why I'm confused he's portrayed himself as an alpha (who SUPPORTS omegas) in his office. And he talks abt betraying this specific person who he has a framed picture of, which seems to be his partner. Even the alpha says like "let him have your alpha side, and only I know your omega side" or smth like that. That's why I asked whether he's an omega and had to act like an alpha like rei or is he one of those ppl who have both characteristics, or if he's like an alpha w some kinda complex of wanting to be an omega or smth like that lol
Idk I'm way too invested clearly

The person he was referring to was his ex-partner. It doesn't explicitly say but we gather from the way the story goes that they're no longer together. He feels guilty because he could never satisfy his partner or fulfill his needs, and we learn that this was the case because he was never an alpha to begin with. From the way the story went ( please correct me if I'm wrong ), I gather that he really believed he was an alpha but lacking ( he couldn't understand why he couldn't make his partner who he loved happy ). Then when Rei finally came to him and explained that he was an omega and mentioned that his omega side was being suppressed by the meds and "allergy meds" given by their family doc, the scene shows Sei ( uncle ) having a reaction/realization. He realized he had also been taking such meds for "allergies" since he was young. Then there's a scene where he tosses the meds he picked up from their fam doc into the trash. I think that's where he decided to see if it was true that he's also an omega and seemed he did want to become an omega as it started to make sense why there were things he couldn't explain about himself. He was also afraid to accept his omega self in fear of losing his reputation and everything he built up as an alpha and in fear that it would be a betrayal to the omega he loved. His alpha, Ruiji, understands this and so tells him he can continue to pretend to be an alpha in public and continue to let his ex-partber think of him or see him as an alpha, but to be his true omega self in front of him (Ruiji).
Hope this helps! (=・ω・=)

pretty sure Sei's partner died; they aren't an ex in the sense of a break-up. if they had a break-up then his being an omega being revealed wouldn't be as big of a deal. he wants to protect his pair's memory.
i personally read the second volume (yes, fairly sure the uncle story and anti adult one are a vol. 2, not extras to vol.1) on another site and it was translated by the same team as the first volume, so there might be some translation issues that led to your confusion. i read a little here and there of the one posted on this site and compared it to the other fan translation. there were some things off in what i looked at, though overall it most certainly wasn't bad and the translator was awesome for doing the work they did, but there were many parts that were much clearer in the other version. of course, sometimes rereads just help as well. i hope you'll better understand/enjoy it again if you do! ^-^
But wtffff were both the uncles. One's a psychopathic danger to society and the other's a cheater (?) with an omega complex. Which wasn't clear tbh is he actually an omega (same issue like rei) or is bro inter-sex? Like what is going awnnnn
Yuujin and rei ftw fr.
The omega who got the uncle removed from the board should also hire an assassin frfr