Kimi ni Madoi, Kimi ni Oboreru.

The story’s protagonist is the 23-year-old Sayo Tsuyuki, who has lived her life so far without a “secondary gender,” but is suddenly told that she has been an omega all along. However, in this world, “all omegas who don’t find a mate before the age of 25 die,” and the only way to escape that fate is to mate with an alpha. So, in order to literally survive, Sayo decides to dedicate the remaining two years of her life to finding a mate. At the same time, she returns to her hometown after five long years, reuniting with some of her old childhood friends, who help her discover true love, but also ignite an “uncontrollable instinct” within her.