but he is a beta. so he can't give birth to alpha babys Love
Actually he can give birth to alpha children if despite him being a beta of he were to marry a female alpha. If noah's father can marry a female alpha and have Noah who is an Alpha so can he, Hajime's brother.
I'm just taking a guess but i't revolve on the idea of Sho trying not to have sex (during the trip) with Noriyuki but the latter actually wanted him to do it. Hence the head and the hole.
THE GANGSTER WHO ONLY BOTTOMS.... thats a real legend right there...