My one and only brother in this world is Yoon-oh, who has been secretly in love with Haewon, his family, and sole protector, for a long time. He believes that they cannot be together because he is a beta while Haewon is an alpha. Consequently, he hides his feelings and remains by Haewon's side. However, when Yoon-oh finds himself unexpectedly ensnared in Haewon's sudden rut, for which he was unprepared, he desperately tries to conceal his emotions—only to be discovered by Haewon.