Mei wakes up one morning and discovers that Yuzu is an omega. There are 20 alphas in Aihara Academy, and Mei knows that several of them would want to claim Yuzu as their mate. Who will become her sister's alpha? Plot-driven angst, action, romance, and smut. Crossover with with Akuma No Riddle, features Isuke x Haruki. Alpha/Beta/Omega dynamics. Omegaverse AU