The Aishi Family comes from a very long line of yanderes. Most women in Ayano Aishi's family desire giving birth at a young age, such as 19. It has also been a family tradition for several centuries that when an Aishi woman marries a man, the man adopts the wife's surname. All Aishi women are emotionless until they find the person who can make them experience feelings. It is likely that there are no male yanderes in the family and the family line has consisted of female-only yanderes for centuries.
There will always be slight differences between each yandere born into the Aishi family, but never in terms of strength. All of the Aishis look almost identical to one another. YandereDev imagines all of Ayano's ancestors with the same exact hairstyle, even if it feels goofy to him. The Aishi family members aren't very close. Once a yandere has found a partner, they tend to distance themselves from the family. It's likely that Ayano hasn't met most of her relatives, although no one is on bad terms. While male children are unlikely, they would look similar to Senpai and would be yandere as the females are.
Relationship between an Aishi woman and her Senpai
After enough years in the presence of her "senpai", an Aishi woman will eventually develop the capacity to experience emotions, even when apart from her senpai. After several decades in possession of a senpai, an Aishi woman would no longer require her senpai's presence in order to experience stimuli the same way that normal humans do.
If an Aishi woman loses her senpai before she has developed the capacity to experience emotions, she would feel as though she has permanently lost the capacity to hear music, see color and feel warmth. This may lead her to fall into an extremely deep depression that leaves her in a coma-like state. However, if an Aishi woman loses her senpai after she is no longer dependent on his presence, she would not fall into the coma, but she would still feel an extremely deep sense of loss and pain that is far beyond what a normal human would feel at the loss of a loved one.
A senpai can influence his Aishi's personal growth and development. If her senpai says "Stop killing people or I'll hate you forever!" enough times, he could "train" his Aishi to stop being a killer. If her senpai is meek and submissive, then he would have no influence over his Aishi's development.
Depending on how the Aishi woman "developed" after acquiring her senpai, she would react to his death differently. She might enter a coma-like state, might fly into a blind rage and kill everyone around her, or might try to live a normal, happy life without him. This is heavily dependent on what type of senpai she acquired, and how her senpai influenced her personal growth and development.
It's also dependent on how he died. If the senpai died of illness, the Aishi would feel as though nobody is to blame. If the senpai was murdered by someone, the Aishi would seek revenge.
If Senpai is customized to be a girl, the Aishis will still find a way to continue their family line. It has not been explained how yet.
YandereDev imagines that Ayano's great-great-great-great-great-great grandmother wore a bloody kimono and wielded a knife.
The last name "Aishi" is a play on words. Ai means "love" and Shi means "death".
Ayano's great-grandma and great-grandpa were the first to move to Buraza Town. Ayano's grandma asked for a basement, which great-grandma agreed to. The grandmother eventually kidnapped the grandfather and kept him in their basement. They then gave birth to Ryoba, who eventually used the basement at least once.
There is a brotherly kinship among the various "Senpai's" because they share each other's experiences with a yandere wife. Still, they are all their own unique individual.
Ayano's family members are all named after blades. Her child would also have a name that sounds like a blade.
The origin of the Aishi condition was passed down generation to generation, however, its origin is now considered a fairy tale, as Aishi's stopped taking it seriously.
YandereDev thinks that Ryoba's mother may have brainwashed her husband into loving her unconditionally.
Ayano’s grandmother would help her kill and dispose of a rival if asked. However, YandereDev does not think she helped Ryoba.
YandereDev think it would be uncharacteristic for Aishis to believe in any religion.
When Aishis meet, they probably exchanging advice on how to get away with murder.
The first Aishi and "important" ancestor of the protagonist was born in 1780.
She met "First Senpai" in 1796, but she didn't form a relationship with him until 1797, and she had a child with him in 1800.
The first time she had an encounter with a "love rival" was in 1797, and that's when for the first time she'd take a life. However, when she took lives in 1797, it was all entirely in self-defense, including the "love rival" she faced at this point in time.
Due to the circumstances surrounding her life and her lifestyle, it's entirely possible she may have been forced to kill a human prior to 1797. But, if so, it wasn't a love rival; it was someone who was threatening her life. The amount of her murders depends on whether or not self-defense is considered murder. Depending on the criteria for "murder", the answer is either zero or hundreds, and only a fraction of those deaths took place in Japan.
YandereDev has an illustration of her, but he wouldn't like to reveal or describe her.
She was born under a different surname, and she started using the surname Aishi since 1797, upon arriving in Japan with "First Senpai", because they had to select a name that the locals could pronounce more easily than their real names. She's also not named after a blade.
In the Edo period (1603-1868), where the first Aishi lived, there was only 4 classes in Japan society - Samurais (侍 Shi), Farming Peasants (農 Nō), Artisans (工 Kō) and Merchants (商 Shō). YandereDev has something in mind for the occupation/role that both she and her Senpai had performed once they arrived in Japan, but he wouldn't like to reveal it. However, he did confirmed that from this four classes, she didn't really fit into the noble class of Samurais or into the Farming Peasants class, which implies she may been either Artisan or Merchant, but he also did said that she was in "a class outside of normal society".
Her parents were somewhere in their 20s when she was born, and they aren't a part of her backstory.
A third party informed the "First Senpai" that she was in love with him. Love bloomed between her and her Senpai naturally.
There is an Info-chan-like figure in First Aishi's life.
She was born without any conditions, and her condition isn't really a "sickness".
She did not wear traditional Japanese clothing until she arrived in Japan. Her "color scheme" was always red+white+blue, like Ayano's default school uniform.
She had to deal with one, technically two rivals to win her Senpai.
There probably wasn't an "official" wedding between her and her Senpai, but they did consider themselves husband and wife.