He's a adult but his age isn't talked about. Also what's wrong with a different take on seme. Ukes often looks like him so I don't see a issue. Also I'm often mistaken as a minor I'm 35. I had police called on me over my id before cause I was buying cigarettes. The cops laughed for the cashier wasted their time.
I think he is 16
Eve said in early chapters that he is an adult/legal and I assume the author is Japanese so that means he is over 20 at the very least.
Eve is 19 last time I checked in the early chapters
Then he must be close to 20 now
How old is eve? I came to the comments just to see if anyone knew