From a young age, Yua and Mutsuo became siblings due to their parents' remarriage. Even as adults, they were close enough to visit each other's homes frequently. However, Mutsuo harbored feelings for his stepsister that he could never confess. Amidst this, their parents decided to divorce again, leaving the two in a relationship that was neither family nor stranger. Unable to bear being treated as just the 'green' little brother anymore, Mutsuo finally expressed the feelings he had been holding back…
