My Hyung's Omega

Do-yoon finds himself caught in the heat cycle of Su, whom he has cherished and loved since childhood, believing him to be his own younger sibling, and ultimately enters into a relationship with him. Despite being a beta, he wishes to assist Su, who is enduring the heat, but this is the first time he has been overwhelmed by an omega... Is this truly a heat cycle? "I'll try harder because you like"