12 Year Sickness
Major Tales of Berseria spoilers
Being one of the three considered major rare diseases in the world according to one of the books at the library in Loegres, the 12 Year Sickness is described as follows:
“12 Year Sickness” …… a rare disease in which the afflicted experiences fever repeatedly and will die 12 years after their birth. It is also said that it is a “curse” cast upon the afflicted for seeing those who are not human.