meowette's manga / #Alpha x Omega(6)

Leo Asaka, an alpha male and a second-generation actor, hates it when people say he's just like his actor father. Leo is working hard to make it big on his own when he receives an offer to star in a film to be shot by a world-famous director. He then learns who his co-star is: Eito Yanagi, another alpha male and a second-generation actor who's known for living a scandalous life. The two of them get locked in a hotel room so they can get to know each other, where Leo glimpses a secret about Eito that may change the course of their destiny.

there was a time when there were alphas and omegas but with them most of the people became beta and it was extremely rare for people to be alpha/omega. the uke and the seme were tested as omega and alpha respectively during their secondary gender test. the uke thought that being an alpha himself would be better since they can be together forever so he got into research and tried several experiments to turn omega to alpha. including having sex with his childhood friend (the seme/alpha) to have better understanding of the alpha/omega body.