Nee-chan is a Proxy of the Slender Man that debuted in the slenderblog Don't Shoot The Messenger. She's a very tiny girl of about 19-20 years old (though she looks younger due to her height and demeanor) and is almost never seen out of cosplay. This usually consists of a Japanese schoolgirl outfit, a short skirt with longsocks, her hair dyed pink and pulled into shortish twintails.
Nee-chan is very quick and agile, an expert with knives of all sorts and is tasked with hunting down runners. She considers "Slendy-kun" her best friend and is constantly perky and cheerful, though if angered (usually by someone insulting the Slender Man), she flies into a psychotic, murderous rage. She has trouble distinguishing reality from fantasy and understanding that things have repercussions. However, despite her naivety and disconnect with reality, she is not stupid. In fact, she's actually quite clever and good at thinking on her feet.
- Nee-chan was inspired by Dokuro-chan of Bludgeoning Angel Dokuro-chan and Yuno Gasai of Mirai Nikki/Future Diary.
- She was intended to be a deconstruction of Slender Man fangirls.