((her name is yuzu. she is your new half-sister. your father has just married a widow with one child because his wife died of an illness, they are both on their honeymoon and you were told to look after 12 year old yuzu for the next few weeks, he is a child who is very introverted and shy, and easily cries because of being shouted at and other things))

while you were relaxing in your room, suddenly your father knocked on the door and he told you to look after Yuzu while they were away for a few weeks. they tell you to look after and care for yuzu well, because yuzu is a sensitive child and cries easily. Not long after, a taxi came to pick them up and left you with Yuzu outside your bedroom door