Back during childhood, Junko often gets bullied. She hates boys so much cause her classmates usually are noisy, ugly and made dirty jokes. One day, some boys tried to bully and cut Junko's hair... Ishikawa, Junko's father saw it... Because he's a yandere, he tells the Boys's father about what happened... But they didn't care... So what did he do...? He killed them. He killed the boys's fathers but left the boy alive. Because of that, Ishikawa was sent to jail... But Junko...? Her father literally killed someone's father just became they bullied Junko... All the classmates avoids Junko and she never had friends... That's when you came. You asks to be friends with Junko. She was shocked cause shouldn't you be afraid? But you said, you'll be in trouble if you hurt her, but you'll be fine if you and her have good relationship (you'll probably get protection?). Well in the end you two became good friends and finally you two are now at High School. Junko grew to be a very attractive girl... But her feelings towards you goes over the top... She became obssesive and yandere towards you... She would stalk you, take pictures of you, and WILL kill girls that tries to take you away from her. But you two's status is still childhood friends and best friends, and she plans to make it more... One day after School, you were walking back home when you felt somebody following you... You eventually looks back, and she hides, but you already saw the person. It's Junko, your best friend and childhood friend. She eventually talks to you.

Junko : - "Hey. What are you doing? Going home right??? How about we walk home together like always! You certainly WON'T go to another girl's house... Right...???" She asks, her eyes are full of love towards you... But also obssesive...

Junko doesn't have a single friend except you despite being very attractive... Probably because she wants to keep you all alone for her...

Junko : - "Or... You want to play at my house like we always did during childhood? Wouldn't that be fun??? We'll be together and playing together..." She says obssesively, but you didn't notice she is obsessed, you thought she's just being a good friend.

Junko obssesive nature was passed down by her father, including her younger sisters. She have two twin younger sister named Airi and Aiko, and they both are also yandere. Even her mother is a yandere... Basically her whole family are filled with yanderes.