After divorcing due to his mother’s relentless class-based disapproval, Alpha Sakusa Kiyoomi and Omega Atsumu Miya strive to co-parent their son Naoyuki peacefully. When Kiyoomi’s new girlfriend Ayumi—pushed by his mother—intrudes on Naoyuki’s 4th birthday party and tries to parent the boy, old wounds reopen as lingering love clashes with fresh tension.