Momoyama Kyoudai

Arima and his younger sister Chihiro are twins born into the Momoyama family, living what appears to be an ordinary life. However, their sense of normalcy is shattered six years before their sixteenth birthday when they accidentally overhear a deeply unsettling conversation between their parents. The adults speak in hushed tones about revealing a hidden truth to the siblings once they finally turn sixteen. From that moment onward, the overheard words cast a long shadow over their childhood, leaving Arima and Chihiro consumed by quiet anxiety as they try to decipher what their parents could possibly be hiding from them. For six agonizing years, the twins grapple with the weight of this secret, quietly convincing themselves that the impending revelation must mean they were adopted. They brace for a difficult but understandable shift in their family dynamic, preparing themselves for the possibility that their parents are not truly their own. Yet, all of their careful speculation proves entirely inadequate. When their sixteenth birthday finally arrives and the long-awaited truth is unveiled, Arima and Chihiro discover a reality far more shocking than anything they had ever dared to imagine.