What if I became an omega...!?

One day, Haruto's childhood friend, Eita, suddenly turns out to be an Omega. While his sisters are in an uproar, Haruto tilts his head and asks, "What's an Omega?" The Omegaverse is a fictional world. It seems that the novel he was reading when he hit his head influenced him, causing him to fall under a form of self-hypnosis. "Omegas have to be careful of Alphas and Heats, but neither of them exist in reality, so it's okay," his sisters thought, but contrary to their words, Eita ends up encountering an Alpha—!