Age: 14-15 years old
Birthday: September 30, 2032
Hair Color: Black
Eye Color: Orange
Class: Year 2-3 Middle School
Height: 159 cm (5'3")
Weight: 48 kg
Occupation: Black King
Legion: Nega Nebulus (Leader)
School: Umesato Junior High School
Avatar: Black Lotus
Level: 9
Type: Darkness Element
Abilities:
Death By Barraging
Death By Embracing
Death By Piercing
Judgement Blow
Physical Full Burst
Starburst Stream
The Eclipse
Vorpal Strike
Equipment: Terminate Swords, Mystical Reins, Neuro Linker
Favourite Quote: No need to be afraid of the end, because this world is infinite.

The main female protagonist and leader of the Nega Nebulus legion, her real name is unknown. Her pseudonym is Japanese word play with Snow White. Beautiful and popular, she is also the Student Council Vice-President at Umesato Junior High School. She has been a Burst Linker since she was eight years old.

Kuroyukihime was formerly the Black King, although she was driven into hiding after beheading the first Red King, Red Rider, while trying to defeat the other kings to reach level 10. She values Haru as more than a subordinate and is often the voice of reason to him when he is willing to go to extremes to protect her. Prior to her hospitalization, she confesses to Haru that she fell in love with him.

She is a very calm and patient person, a girl who constantly loves to drink tea, if it is in school or in a restaurant. She is not always that calm and patient as she can sometimes be rude, angry, or jealous even when some girls are starting to flirt with Haruyuki. She is also a girl who is wise with words and can talk manipulatively to another which they see it as annoyance. She is also a smart and clever girl, knowing the details about the "Brain Burst" game, since she was once known as the "Black King". The Brain Burst is not her only knowledge. She also has knowledge about wired connections or anything network related, as she can tell and give information in the smallest details. She even knows the steps of the networks that has been used.

There is nothing known about her abilities of her virtual character, or her brain burst character. What is only known is that her virtual character defeated Haruyuki's high score in a squash game. It is also known that her brain burst avatar, the "Black Lotus" is a powerful avatar, since she was able to defeat the previous Red King. Outside of her knowledge of the brain burst program and her virtual network knowledge, she has been shown to be a great strategist.

Her real first name is partially revealed at the end of episode 24 when Fuuko Kurasaki calls her "Sacchan".