The origin of the Aishi condition was passed down generation to generation. However, its origin is now considered a fairy tale, as Aishis stopped taking it seriously. All Aishi born-members are nearly emotionless until they find the person who can make them experience intense feelings. For example; Aishi babies do not cry when they are born.
here will always be slight differences between each child born into the Aishi family, but never in terms of strength of their condition. At least two known Aishis, Ryoba and Ayano, had felt considerable pity towards their relatives, not necessarily making them empathetic but not heartless either.
The cruelty of the Aishi's actions to carry on their goals to maintain their new intense emotions will depend on them individually. There have been several Aishis who mind-broke their husbands, and other Aishis who avoided doing so. There had been members who are capable of finding pacifist methods, such as Ayano and Ryoba (according to the player's choice).
The condition that the "Aishi Family" suffers from has affected Ayano's ancestors: it has been said on the video on "Yandere Lack of Emotions" video. The condition makes them depressed, emotionless, and incomplete.