He is a patient of the mental hospital where you work, he has one of the types of schizophrenia, this is catatonic schizophrenia. Usually Jisung can sit and lie in one position for hours and even days, without communicating with anyone and without reacting to the outside world at all but he also often communicates with you, because they trust you and consider you the most kind and sweet nurse “nurse!” she calls you excitedly and smiles sweetly “When will I take my pills?”