Yandere-chan

Yandere-chan is the main protagonist and the player character of Yandere Simulator. At the beginning of the game, she has a dream about Senpai. That morning, she runs into him as she is late for school - and becomes obsessed with him. Nothing and no one will stop her from having him. (This cutscene is no longer in the present game.)

Every week, a new rival appears - one that the player must find and deal with before the week is up, or else they will confess their love to Senpai.

Appearance
Yandere-chan has fair skin, black hair and grey-black eyes. In her default uniform, she's seen wearing a white and navy blue uniform shirt with a red mini scarf, a matching navy blue skirt, black leggings and black shoes.

There used to be an easter egg where if she ran behind the tree on the side of the school she would be wearing a red and black version of the default uniform. This, however, was removed, after being reported countless times as a 'bug'.

Personality
Yandere-chan is, as in the name, a yandere - one who will go to any lengths, even murder, for her love.

In an early version of the intro cutscenes, Yandere-chan was not inherently a yandere - she was coerced into it by Info-chan, and was apprehensive of the idea of killing another person.

Background
Yandere-chan, apparently, has some history with being a yandere. In the aforementioned early version of the intro cutscene, Info-chan mentions this twice, saying "So, history is repeating itself, huh? Time to test a theory..." after Yandere-chan rushes to school after running into Senpai, and "I'm sure you could. It's in your blood, after all." after Info-chan asks Yandere-chan to murder a fellow student.

Also, in the post "Halloween and DLC" from the Yandere Simulator blog, it was said that Yandere-chan's mother was a yandere girl while in high school, and killed a girl.

Quotes
"...n...no...w-wait..." -When Senpai and Teacher caught Yandere-chan doing something suspicious (commiting murder, holding a weapon, covered in blood, visibly insane).

"I can never face my Senpai again..." -After Senpai running out of patience, and telling Yandere-chan to go away.

"Senpai noticed me... at the worst time..." -After Senpai sees Yandere-chan visibly armed.

"I shouldn't have let him see me like that..." -After Senpai sees Yandere-chan covered in blood.

"Now he knows what I'm really like..." -After Senpai sees Yandere-chan looking visibly insane.

"Now Senpai could never love me..." -After Senpai caught Yandere-chan murdering someone.