I’m An Omega And It’s All My Fault summary:

Jin is at the top of his class at an elite alpha academy. He's smart, good at sports, and good-looking to boot. Basically, he's the perfect alpha. And Shusei is not happy being stuck in second place. Worst of all, Jin finds out Shusei's secret: he's actually an omega! Shusei doesn't want to get close to Jin, but somehow, every time he catches Jin's scent, he starts going into heat! Shusei hates Jin's guts, but why is Jin trying to be so friendly with him?