Yuuta, aged 26 and working in a host club, has just been given a whole series of shocks – his father (whom he hasn’t seen in 6 years) has gotten remarried to a woman one year younger than him. She had a daughter of her own. Then she was badly hurt in an accident. Then his father had to leave, and within the span of a few minutes his life is turned completely upside-down as he now has a young, foreign-born, little sister named Diana to take care of…